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1007/

This is to certify that the

dissertation entitled

MAGNETIC ARCHITECTURES BASED ON METAL CYANIDE
INTERACTIONS:
MIXED METAL CLUSTERS AND POLYMERIC ARRAYS
presentedby ‘

Jennifer Ann Smith

has been accepted towards fulfillment
of the requirements for

 

 

Ph.D. degreein Chemistry

 

 

 

Major professor

 

7
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6/01 cJCIRC/DateDuepes-sz

MAGNETIC ARCHITECTURES BASED ON METAL CYANIDE
INTERACTIONS:

MIXED METAL CLUSTERS AND POLYMERIC ARRAYS

By

Jennifer Ann Smith

A DISSERTATION
Submitted to
Michigan State University
in partial fulfillment of the requirements

for the degree of

DOCTOR OF PHILOSOPHY
Department of Chemistry

2002

ABSTRACT

MAGNETIC ARCHITECTURES BASED ON METAL CYANIDE
INTERACTIONS:

MIXED METAL CLUSTERS AND POLYMERIC ARRAYS

By

Jennifer A. Smith

Many magnetic materials, most notably the three dimensional
Prussian blue cubic solids, are based on the cyanide ligand. The interest in
these systems stems, in part, from the fact that the linear bridging mode of
cyanide allows for strong magnetic exchange coupling between
paramagnetic metal centers. The interaction favors antiferromagnetic
interactions when the magnetic orbitals of the two metals in the M-CN-M'
linkage are of the same symmetry, and ferromagnetic interactions when the
magnetic orbitals are orthogonal. The ability to predict the nature of the
magnetic coupling through the CN' ligand is one of the main advantages of
using this two atom bridge rather than the oxide bridge whose magnetic

interactions are highly dependent on the M-O-M' angle.

Research in our laboratory focuses on the building-block approach for
preparing specific structural motifs, such as the molecular square and cube,
and on using cyanometallates to create new polymeric arrays or discrete
clusters. A series of 3d transition metal compounds were prepared with two
bidentate ligands along with two weakly coordinating ligand or two cyanide
ligands for generating a molecular square motif. An example of this type of
reaction is the combination of the cis—M(N-N)2(CN) with cis—[M'(N-
N)2(OH2)2]'”+ in which the H20 ligands are displaced in favor of the nitrogen
end of the cyanide ligands. One possible outcome of the reaction is
formation of a bimetallic molecular square. In another approach, the
transition metal complexes were protected with a facially capping ligand and
coordinated to three acetonitn'le or cyanide ligands with the aim of preparing
molecular cubes.

Another aspect of the project involves the reaction of
hexacyanometallate ions [M(CN)6]“' with metal cations M2+ (M = Mn, Co
and Ni), in the presence of bidentate ligands, such as 2,2'-bipyridine, 1,10-
phenanthroline or 2,2'-bipyrimidine. In this manner, a variety of novel
bimetallic clusters and low-dimensional polymeric species with distinctive

topologies and magnetic properties were obtained.

ACKNOWLEDGEMENT

The work in this dissertation could not have been done without the
assistance and support of a lot of people. First, I would like to thank my
advisor, Professor Kim R. Dunbar, for her guidance, support and helpful
discussions. It is because of her enthusiasm that inspired me to continue
trying different avenues when other ones had failed. I would also like to
thank my committee: Professor M. G. Kanatzidis, Professor J. L. McCracken
and Professor B. Borhan for their helpful comments. I would like to thank
Dr. J. H. Reibenspies and Dr. D. Ward for their assistance and insight with
single crystal X-ray crystallography. I would like to thank Dr. Holm and
Catalina Achim for performing the Mossbauer experiments.

I cherish all the friendships I have made with the members of the
Dunbar group from Michigan State and Texas A & M. When I joined the
group our post-doc was Han Zhao who helped me immensely with chemistry
especially when I solidified my mercury bubbler. Rodolphe Clérac was our
second post-doc who taught us our samples for magnetic measurements
were “crap”. With time and much effort, he realized I was a chemist and
human. Often nicknamed “Rudy” he helped me write papers, editing what he
knew the boss would not like, editing slides and insightful discussions about

magnetism. Our third post-doc, Jose-Ramon Galan-Mascaros is a character.

iv

He never drinks milk, only Coca-Cola, which he said, is the remedy for any
illness. He is the reason why I will graduate, his guidance and understanding
of the chemistry led the way for my last minute results.

I would like to thank Matt for teaching me how to use a Schlenk line.
I have been very fortunate for the friends I made while in graduate school,
Jennifer Hess, Jennifer Aitken, Elizabeth, Shannon and Amanda from our
aerobic exercise to tae-bo and our shopping excursions. I really miss doing
the crossword puzzles with you all everyday at lunch. Our ice cream breaks
were delicious and so satisfying. I would also like to thank Paul and Brad for
listening to me. I enjoyed our sports conversations and thanks for being my
punching bags. I would also like the thank Cristian and the newer group
members for some really fun and interesting times in Texas, Kam, Eric,
Merv, Curtis, Meijong and Lindsey.
I would also like to thank Joy Heising and Teresia Moller for making my
time in Texas so special. I enjoyed our weekend adventures from Tina
Turner to squishing frogs that are jumping all over the road while driving to
Memphis and using bubble gum to mend our windshield wiper back together
at 2 am in pouring rain.

I also would like to give credit to my feline companions, Simba and

Bogey. Whenever I had a bad day, I could come home to them and they

would entertain me, almost instantly changing my mood. Most importantly, I
want to give my deepest appreciation to my husband, parents and

grandparents for their support and understanding.

vi

TABLE OF CONTENTS

LIST OF TABLES ............................................................... xv
LIST OF FIGURES ............................................................ xix
LIST OF COMPOUNDS ....................................................... xxiv
LIST OF ABBREVIATIONS .................................................. xxvii
CHAPTER I. INTRODUCTION ............................................. 1
INTRODUCTION ............................................................... 2
1. History of Molecular Magnetism .......................................... 2
2. Prussian Blue .................................................................. 3
3. Prussian Blue Analogues .................................................... 8
4. Controlled Syntheses of Specific Motifs .................................. ll

5. Building Polymeric Assemblies and Clusters with
Hexacyanometallates ....................................................... 27
6. References ..................................................................... 39

CHAPTER II. Synthesis, Characterization and Reactivity Studies of Square
Precursors of the Type cis-[(N—N)2M(S)2]'1+ (S: H20,

(CF3SO3)', CH3CN, (N03)', (CN)') ........................ 49
1. INTRODUCTION .......................................................... 50
2. EXPERIMENTAL .......................................................... 55
A. PHYSICAL METHODS ................................................... 55
B. SYNTHESES ................................................................ 55

vii

(1) Preparation of [(2,2'-bpym)2M(OH2)2](BF4)2 for M = Mn"(1), Fe"(2),

Col (3) and Ni"(4) ........................................................ 56
(2) Preparation ofu[(2,2'-bpy)2M(CH3CN)2](BF4)2 for M = Mn“(5),

Co (6) and N1 (7) ....................................................... 59
(3) Preparation of [(phen)2Ni (CH3CN)2](BF4)2 (8) ..................... 61
(4) Preparation of [(2,2'-bpy)2Ni(CH3CN)2](PF6)2 (9) .................. 61
(5) Preparation of (2,2'-bpy)2M(CF3SO3)2 for M = Mn"(10) and

Co (11) .................................................................. 62
(6) Preparation of (phen)2Mn(CF3SO3)2 (12) ........................... 63
(7) Preparation of [(2,2'-bpY)2Ni(OH2)2](CF3SO3)2 (13) ............... 64
(8) Preparation of (phen)2Mn(NO3)2 (l4) ................................ 65
(9) Preparation of (phen)2Co(NO3)2 (15) ................................. 65

(10) Preparation of (2,2-bpy)2M(CN)2 (M = Mn (16) and Co (17)).. 66

(11) Preparation of [(4,4'-Me2-2,2'-bpy)2CrC12]Cl (18) ................ 67
(12) Preparation of [(4,4'-Me2-2,2'-bpy)2FeC12]Cl (l9) ................ 68
(13) Preparation of [(4,4'-Me2-2,2'-bpy)2Fe(CN)2](PF6) (20) ......... 69
C. REACTIONS ............................................................... 69

(1) Reaction of (2,2'-bpy)2Co(CN)2 with [(2,2'-bpy)2Co(CH3CN)2](BF4)2
............................................................................. 69

(2) Reaction of (2,2'-bpy)2Co(CN)2 with [(Phen)2Ni(CH3CN)2](BF4)2. 70

(3) Reaction of (2,2'—bpy)2Co(CN)2 with (phen)2Mn (CF3SO3)2 ...... 70

(4) Reaction of (4,4'-‘Bu-2,2'-bpy)2Co(CN)2 with
[(2,2'-bp)’)2Nl(CH3CN)2](PF6)2 ....................................... 7 1

viii

D. SINGLE CRYSTAL X-RAY STRUCTURAL STUDIES. . . . . . . . 71

(1) [(2,2'-bPY)2Ni(CH3CN)2](BF4)2 (7) ....................................... 72
(2) (2,2'-bpy)2Mn(CF3so3)2 (10) ............................................. 76
(3) [(2,2’-bpy)2Ni(OH2)2](CF3SO3)2 (13) .................................... 76
(4) [(2,2'-bpy)2Mn(CN)2] (16) 03HZO ....................................... 77
(5) [(4,4'-‘Bu-2,2'-bpy)2Co(CN)2](PF6) (22) ................................. 78
3. RESULTS AND DISCUSSION ............................................ 84

A. Syntheses of [(N-N)2M(S)2]2+ Salts (N-N = 2,2'-bipyridine,
2,2'-bipyrimidine or 1,10-phenanthroline and S = H20, CH3CN,

CH3OH or (N03) ............................................................. 84
B. Syntheses of Trivalent Precursors .......................................... 92
C. Reactivity Studies ............................................................ 94
D. Molecular Structures ......................................................... 96
E. Magnetic Properties .......................................................... 100
4. SUMMARY AND CONCLUSIONS ...................................... 109
5. REFERENCES ............................................................... 1 1 1
CHAPTER III. MOLECULAR CUBE PRECURSORS and
REACTIVITY STUDIES .................................. 115
1. INTRODUCTION ........................................................... 1 16
2. EXPERIMENTAL ........................................................... 1 19
A. PHYSICAL METHODS .................................................... 1 l9

ix

B. SYNTHESES ................................................................ 120

(1) Preparation of [TpFe(CH3CN)3](CF3SO3) (22) ....................... 120
(2) Preparation of K[TpFe(CN)3] (23) ..................................... 121
(3) Preparation of [TpCo(CH3CN)3]X (x = (BF4)' (24), (CF3SO3)‘ (25),
(Pa) (26)) ................................................................ 122
(4) Preparation of [EtaN]2[TpCo(CN)3] (27) ............................. 124
(5) Preparation of [TpNi(CH3CN)3]X (x = (BE) (28), (CF3SO3)‘ (29),
(Pm (30)) ............................................................... 125
(6) Preparation of NiTp2 (31) .............................................. 127
(7) Preparation of [(9S3)Co(CH3CN)3](PF6)2 (32) ...................... 128
(8) Preparation of (9S3)CoC12 (33) ....................................... 129
(9) Preparation of [Co(9S3)2]C12 (34) ..................................... 129
C. REACTIVITY STUDIES ................................................. 130
(1) [TpFe(CH3CN)3](CF3SO3) and K[TpFe(CN)3] ..................... 130
(2) [EnN]2[TpCo(CN)3] and [(dien)Ni(NO3)2] ......................... 131
(3) [EtaN]3[(CO)3Mo(CN)3] and [(9S3)Co(CH3CN)3](PF6)2 .......... 131
(4) [EtaN]3[(CO)3Mo(CN)3] and (THF)3CrC13 ........................... 132
(5) [EtaN]3[(CO)3Mo(CN)3] and TpCrCI3 ................................ 132
(6) [EtaN]3[(CO)3Mo(CN)3] and (dien)Ni(NO3)2 ........................ 133
D. SINGLE CRYSTAL X-RAY STRUCTURAL STUDIES ............ 134
(1) [TpNi(CH3CN)3](PF6) (3o) ............................................. 134

(2) [FeTp2](BF4) (35) ........................................................ 137

3. RESULTS AND DISCUSSION ........................................... 138
A. Syntheses .................................................................. 138
B. Reactivity Studies ......................................................... 150
C. Molecular Structures ..................................................... 154
D. Magnetic Properties ...................................................... 156

4. SUMMARY AND CONCLUSIONS .................................... 160

5. REFERENCES .............................................................. 162

CHAPTER IV. CYANIDE ASSEMBLIES and CLUSTERS ............ 165

1 .INTRODUCTION ........................................................... 166

2. EXPERIMENTAL ......................................................... 167
A. Physical Methods ........................................................ 167
B. Syntheses .................................................................. 168
(1) Synthesis of {(Mn(H20)2)[Mn(2,2'-bpym)(H20)]2[Fe(CN)6]2}..

(36) ........................................................................ 168
(2) Syntheses of {[Co(2,2'-bpy)2]3,[Fe(CN)6]2}+ (37) .................... 169

A. Reaction of (2,2'-bpy)2Co(CF3SO3)2 and [Et4N]3[Fe(CN)6]. .. 169
B. Reaction of [Co(2,2'—bpy)3](C104)2 and K4[Fe(CN)6] ......... 169
C. Reaction of (2,2'-bpy)2Co(CF3SO3)2 and K3[Fe(CN)6] ........ 170

D. Reaction of (2,2'-bpy)2Co(CF3SOg)2 and [K-18-C-6]3[Fe(CN)6]
........................................................................ 170

xi

E. Reaction of (2,2'-bpy)2Co(CF3SO3)2 and [K—18-C-6]3[Fe(CN)5]

......................................................................... 17 1
F. Reaction of (2,2'-bpy)2Co(CF3SO3)2 and K3[Fe(CN)6] ....... 172
G. Reaction of [Co(2,2'-bpy)3](ClO4)2 and K3[Fe(CN)6] .......... 172

H. Reaction of [Co(2,2'-bpy)3](ClO4)2 and [K-18-C-6]3[Fe(CN)6].. 173

I. Reaction of (2,2'-bpy)2Co(CF3SO3)2 and K4[Fe(CN)6] ......... 173

(3) [Ni(2,2'-bpy)2]2[Fe(CN)6]2[Ni(2,2'-bpy)2(HzO)] (38) ............... 174
(4) [Zn(phen)3][Zn(phen)2]2[Fe(CN)6]2 (39) .............................. 175
C. Reactivity Studies ............................................................ 175

(1) Reaction of (2,2'-bpy)2Mn(CF3SO3)2 with [K-18-C-6]3[Fe(CN)6].. 175

(2) Reaction of (2,2'-bpy)2Mn(CF3SO3)2 with K3[Fe(CN)6] ............ 176
(3) Reaction of (2,2'-bpy)2Mn(CF3SO3)2 with K3[Fe(CN)6] ............ 177
(4) Reaction of [Mn(2,2'-bpy)3](ClOa)2 with K3[Fe(CN)6] .............. 177

(5) Reaction of [Mn(2,2'-bPY)3](C104)2 with [K-18-C-6]3[Fe(CN)6]. .. 178
(6) Reaction of (phen)2Mn(CF3SO3)2 with K3[Fe(CN)6] ................. 178
(7) Reaction of (phen)2Mn(CF3SO3)2 with [K-l8—C-6]3[Fe(CN)6] ...... 179
(8) Reaction of (phen)2Mn(CF3SO3)2 with [K-18-C-6]3[Fe(CN)6] ...... 179

(9) Reaction of [Co(2,2'-bpym)3](BF4)2 with [Kl8-C-6]3[Fe(CN)6]. . 180

(10) Reaction of [Co(2,2'-bpym)3](BF4)2 with K3[Fe(CN)6] ............. 181
(11) Reaction of (phen)2Co(NO3)2 with K3[Fe(CN)6] ..................... 182
(12) Reaction of (phen)2Co(NO3)2 with K3[Fe(CN)6] ..................... 182

xii

(13) Reaction of [TpCo(CH3CN)3](PF6) with [K-18-C-6]3[Fe(CN)6]. .. 183
(14) Reaction of (dien)Ni(NO3)2 with [K-18-C-6]3[Fe(CN)6] ............ 184
(15) Reaction of (2,2'-bpy)2Ni(CF3SO3)2 with [K-18-C-6]3[Fe(CN)6].. 184

(16) Reaction of [(2,2’-bpy)2Ni(CH3CN)2](PF6)2 with K3[Fe(CN)6]. .. 185

(17) Reaction of (phen)ZZn(NO3)2 with K3[Fe(CN)6] .................... 185
(18) Reaction of (phen)2Zn(NO3)2 with K3[Fe(CN)6] ................... 186
(19) Reaction of (phen)ZZn(NO3)2 with K3[Fe(CN)6] ................... 186
(20) Reaction of (phen)2Zn(NO3)2 with K3[Fe(CN)6] ................... 187
(21) Reaction of (phen)ZZn(NO3)2 with K4[Fe(CN)6] .................... 187
(22) Reaction of (phen)22n (N03)2 with K4[Fe(CN)6] .................... 188
(23) Reaction of (phen)ZZnC12 with K3[Fe(CN)6] ........................ 188
(24) Reaction of (phen)ZZnC12 with K3[Fe(CN)6] ........................ 189
(25) Reaction of [Zn(phen)3]C12 with K3[Fe(CN)6] ...................... 189
(26) Reaction of [Zn(phen)3]C12 with K3[Fe(CN)6] ....................... 190
(27) Reaction of (2,2'-bpy)2Zn(NO3)2 with K3[Fe(CN)6] ................ 190
(28) Reaction of (2,2'-bpy)2Zn(NO3)2 with K4[Fe(CN)6] ................ 191
(29) Reaction of (2,2'-bpy)ZZnC12 with K3[Fe(CN)6] ..................... 191
(30) Reaction of (2,2'-bpy)ZZnC12 with K4[Fe(CN)6] .................... 192
C. SINGLE CRYSTAL X-RAY STRUCTURAL STUDIES ............ 192
( 1) {(Mn(HzO)2)[Mn(2,2'-bpym)(HzO)]2[Fe(CN)6]2 } (36) .............. 193

xiii

(2) [Co(2,2'-bpy)2]3[Fe(CN)6]2(37) ........................................ 199

(3) [Ni(2,2'-bpy)2]2[Fe(CN)6]2[Ni(2,2'-bpy)2(HzO)] (38) ............... 200
(4) [Zn(phen)3][Zn(phen)2]2[Fe(CN)6]2 (39) .............................. 201
(5) {[Zn(Phen)2][Fe(CN)6] } { [Zn(Phen)2] [Zn(Phen)2(0H2)][Fe(CN)6] }2
(40) ........................................................................ 201
3. RESULTS AND DISCUSSION .......................................... 208
A. Syntheses .................................................................... 208
B. Reactions .................................................................... 216
C. Molecular Structures ...................................................... 231
D. Magnetic Data .............................................................. 245
4. SUMMARY AND CONCLUSIONS .................................... 255
5. REFERENCES .............................................................. 256

xiv

Ta

181

LIST OF TABLES

Table 1.1. Prussian blue and PB analogues with their Tc values ........... 9
Table 1.2. Polynuclear cyanide complex along with their Tc values ...... ' 37
Table 2.1. Crystallographic information for [(2,2'-bpy)2Ni(CH3CN)2](BF4)2
(7) and [(2,2'-bpy)2N1(OH2)2](CF3SO3)2 (13) .2H20 .......... 73
Table 2.2. Crystallographic information for (2,2'-bpy)2Mn(CF3803)2 (10)
and (2,2'-bpy)2Mn(CN)2 (16) .3HzO ............................ 74
Table 2.3. Crystallographic information for
[(4,4'-'Bu-2,2'-bpy)2Co(CN)2](PF6) (21) 0H20 ................. 75
Table 2. 4. IR data for compounds[ [,(2 2 -bpym)2M(OI-I2)2](BF4)2 (M: Mn11
(1), Fe“ (2), Co (3) and Ni“ (4)) ................................. 87

Table 2.5. IR data for compounds [(N-N)2M(CH3CN)2](BF4)2 (M = Mn" (5),
Co“ (6) and Ni“ (7 and 8)) and N-N = 2,2'-bpy and
1 ,10-phenanthroline ................................................ 88

Table 2. 6. IR data for (N- -N)2M(CF3SO3)2 (M: Mn 11(10 and 12), Co" (11)
and N- N: 2, 2'- -bpy and 1,10-phenanthroline .................. 91

Table 2.7. Selected bond distances [A] and angles [°] for
[Ni(2,2'-bPY)2(CH3CN)2](BF4)2 (7) .............................. 101

Table 2.8. Selected bond distances [A] and angles [°] for
(2,2'-bpy)2Mn(CF3SO3)2 (10) ..................................... 102

Table 2.9. Selected bond distances [A] and angles [°] for
[(2,2'-bPY)2Ni(OH2)2](CF3SO3)2 (13) ........................... 103

Table 2.10. Selected bond distances [A] and angles [°] for
[(2,2'-bpy)2Mn(CN)2]03HzO (16) .............................. 104

Table 2.11 . Selected bond distances [A] for
[(4,4'-'Bu—2,2'-bpy)2Co(CN)2](PF6) (21) ..................... 105

XV

Table 2.12. Selected bond angles [°] for
[(4,4'-‘Bu-2,2'-bpy)2Co(CN)2](PF6) (21) ..................... 106

Table 2.13. Summary of magnetic data at room temperature for molecular
square precursors ............................................... 107

Table 3.1. Crystallographic information for [TpNi(CH3CN)3](PF6) (30).. 135
Table 3.2. Crystallographic information for [FeTp2](BF4) (35) ....... 136

Table 3.3. IR data for [TpM(CH3CN)3]X M = F6 (22), C0 (24-26) and
Ni (28-30) x = (131:4); ((1123503); (PF6)' ..................... 143

Table 3.4. Selected bond distances [A] and angles [°] for
[TpNi(CH3CN)3](PF6) (30). .................................... 157

Table 3.5. Selected bond distances [A] and angles [°] for
[FeTp2](BF4) (35). ............................................... 158

Table 3.6. Summary of magnetic susceptibility data for cube precursors at
room temperature ................................................ 1 59

Table 4.1. Crystallographic information for {Mn(HzO)2
[Mn(2,2‘-bpym)(H20)]2[Fe(CN)6]2} (36) ..................... 1 94

Table 4.2. Crystallographic information for
{[Co(2,2'-bpy)2]3[Fe(CN)6]2}+ (37) .............................. 195

Table 4.3. Crystallographic information for {[Ni(2,2'-bpy)2(OH2)]
[Ni(2,2'-bpy)2][Fe(CN)6]2} (38) ................................. 196

Table 4.4. Crystallographic information for {[Zn(phen)3]
[Zn(phen)2]2[Fe(CN)6]2} (39) .................................... 197

Table 4.5. Crystallographic information for {[Zn(phen)2][Fe(CN)6] }2
{ [Zn(phen)2]Zn(phen)2(OH2)] [Fe(CN)6] }2 (40) ............... 198

Table 4.6. Summary of IR data for {[Co(2,2'-bpy)2]3[FC(CN)6]2 }+ (37). 211

xvi

Table 4.7. Summary of IR data for { [Co(2,2'-bpy)2]3[Fe(CN)6]2 }+ (37). 212

Table 4.8. Mossbaur data summarized for [[Co(2,2'-bpy)2]3[Fe(CN)6]2}+

(37 ) .................................................................. 214
Table 4.9. IR data for reactions between (2,2’-bpy)2Mn(CF3S03)2
and [Fe(CN)6]3’ .................................................... 218
Table 4.10. Summary of IR data for reactions between (phen)2Mn(CF3SO3)2
and K3[Fe(CN)6] ................................................. 221
Table 4.11. Summary of IR data of reactions between Co" precursors
and K3[FC(CN)6]. ................................................ 224
Table 4.12. Summary of IR data for reactions of (phen)2Zn(NO3)2
with [Fe(CN)6]3'/4‘ ............................................... 228
Table 4.13. Summary of IR data for reactions between (phen)ZZnC12
or [Zn(phen)3]C12 and K3[Fe(CN)6] ........................... 229
Table 4.14. Selected bond distances [A] for {Mn(H20)2
[Mn(2,2'—bpym)(H20)]2[Fe(CN)6]2} (36) ..................... 235
Table 4.15. Selected bond angles [°] for{ Mn(HzO)2
[Mn(2,2'-bpym)(H20)]2[Fe(CN)6]2} (36) ..................... 236
Table 4.16. Selected bond distances [A] for {[Co(2,2'-bpy)2]3[Fe(CN)6]2 }+
(37) ................................................................. 240
Table 4.17. Selected bond angles [°] for {[Co(2,2'-bpy)2]3[Fe(CN)6]2}+
(37) ................................................................. 241
Table 4.18. Selected bond lengths [A] for {[Ni(2,2'-bpy)2(OH2)]
[Ni(2,2'—bpy)2][Fe(CN)6]2} (38) .............................. 242
Table 4.19. Selected bond angles [°] for {[Ni(2,2'-bpy)2(OH2)]
[Ni(2,2'-bpy)2][Fe(CN)6]2} (38) .............................. 243
Table 4-20. Selected bond lengths [A] for {[Zn(phen)3][Zn(phen)2]2
[Fe(CN)6]2} (39) ................................................ 246
xvii

Table 4.21. Selected bond angles [°] for {[Zn(phen)3][Zn(phen)2]2
[Fe(CN)6]2} (39) ................................................. 247

Table 4.22. Selected bond lengths [A] for {[Zn(phen)2][Fe(CN)6] }2
{ [Zn(phen)2]Zn(phen)2(OH2)] [Fe(CN)6] }2 (40) ............ 249

Table 4.23. Selected bond angles [°] for {[Zn(phen)2][Fe(CN)6]}2
{ [Zn(phen)2]Zn(phen)2(OH2)][Fe(CN)6] }2 (40) ............ 250

xviii

LIST OF FIGURES

Figure 1.1. Schematic diagram depicting the unit cell of the Keggin and
Miles model of Prussian Blue (Image is presented in color)... 6

Figure 1.2. Schematic diagram representing antiferromagnetic and

ferromagnetic coupling of open-shell transition metals bridged
by cyanide ......................................................... 7

Figure 1.3. Coordination modes of the cyanide ion ....................... 12

Figure 1.4. Examples of cyclic metal cyanide ClUStCFS char acterized by
X-ray diffraction studies ....................................... 13

Figure 1.5. Schematic diagram representing the molecular square assembly
process ............................................................ 14

Figure 1.6. Structural representations of the molecular squares (a)
[FezuCuzu(u—CN)4(bpy)6](PF6)402H2004CHC13 and (b)
[FeZIIICu21‘(u-CN)4(bpy)6](pF6)6o4CH3CN-2CHC13. . . . 16

Figure 1.7.Thermal ellipsoid plots of

[(CP)4(C5(CH3)4CH3CH2)4C04Rh4(CN)121(PF6)4 depicted (a)
with corner protecting Cp and Cp* ligands, (b) skeletal View and
(c) space filling diagram ....................................... 19

Figure 1.8. Thermal ellipsoid plots of K[(Cp*)4(CO)12Rh4Mo4(CN)12]
(a) with the corner protecting Cp* groups and (b) skeletal
view. The potassium atom is disordered over two sites. . .. 20

Figure 1.9. Thermal ellipsoid plot of the molecular cube structure
[(tacn)gCog(CN)12](O3SCF3)3 and a space filling diagram.. 21

Figure 1.10. Examples of manganese carboxylate clusters ............... 24
Figure 1.11 , Double-well potential energy versus magnetization diagram
for [M012012(02CCH3)16(H20)4]2.(H02CCH3).4H20 (S=10)-

The thermal barrier height for magnetization reversal scales as
52D (100D with D = .050 cm'1 ............................... 25

xix

Figure 1.12. An ORTEP drawing of the asymmetric unit of
[Ni(en)2]3[Fe(CN)6]2-2HZO (above), projection of the
polymeric structure onto the be plane, the ethylenediamine
molecules were omitted (right) .............................. 29

Figure 1.13. An ORTEP plot for {[Ni(pn)2]2[Fe(CN)6] }*, projection of the
Fem4Nin4 squares along the c axis of the 2-D network... 31

Figure 1.14. ORTEP plot of the structure [Ni(tren)]3[Fe(CN)6]206I-I20.. 32

Figure 1.15. (a) ORTEP drawing of the heptanuclear unit of
[Mn(en)]3[Cr(CN)6]204H20, (b) a Cr3Mn4 defective cubane
unit, and (c) projection of the polymeric Structure onto the
ac plane (H20 and en were omitted for clarity) ........... 34

Figure 1.16. A thermal ellipsoid plot of the discrete, neutral pentamer
cluster, [Ni(bpm)2]3[Fe(CN)6]207H20 ...................... 35

Figure 2.1. Schematic representation of halide abstraction from
[(N-N)2MC12] to yield [(N-N)2M (S)2] species .............. 53

Figure 2.2. Schematic representation of the molecular square assembly
process ............................................................ 54

Figure 2.3. Thermal ellipsoid representation of the cation
[(2,2'-bpy)2Ni(CH3CN)2]2*, in (7) at the 50 % probability level,
The hydrogen atoms were omitted for the sake of clarity
(Image is presented in color) .................................. 79

Figure 2.4. Thermal ellipsoid representation of (2,2'—bpy)2Mn(CF3SO3)2,
(10), at 50 % probability level. Hydrogen atoms were omitted
for the sake of clarity .......................................... 80

Figure 2.5. Thermal ellipsoid representation of [(2,2'-bpy)2Ni(OH2)2]2+,
(13) at 50 % probability level. Hydrogen atoms were omitted
for the sake of clarity ......................................... . 81

Figure 2.6. Thermal ellipsoid representation of (2,2'-bpy)2Mn(CN)2(16)

at 50 % probability level. The hydrogen atoms were omitted
for the sake of clarity .......................................... 82

XX

 

Figure 2.7. Thermal ellipsoid representation of
[(4,4'-‘Bu-2,2'-bpy)2Co(CN)2]+, in (21) at 50 % probability
level. The hydrogen atoms were omitted for the sake of
clarity ............................................................ 83

Figure 3.1. Schematic representation of the molecular cube assembly
process .......................................................... 1 18

Figure 3.2. Thermal ellipsoid plot of [TpNi(CH3CN)3]+ in (30) at 50 %
Probability level. The hydrogen atoms were omitted for the
sake of clarity .................................................. 139

Figure 3.3. Thermal ellipsoid representation of the cation [Fesz]+ in
(35) at the 50 % probability level. The hydrogen atoms
were omitted for the sake of clarity ......................... 140

Figure 3.4. Schematic representation of reactions with solvated precursors,
[M(CH3CN)612*, with a facial tridentate ligand to yield
[L3M(S)3]“+ ..................................................... 142

Figure 3.5. Schematic representation of the reaction between FeC13 and
Nan' to yield [TpFeClg] .................................... 146

Figure 3.6. Schematic representation of [TpMC13]’ with cyanide to yield
[TpM(CN)3]‘ ................................................... 147

Figure 4.1. A structural representation of the 2-D polymer
{[Mn(H20)2[Mn(2,2'-bpym)(H20)]2[Fe(CN)6]2} (36) taken
from the X-ray structure. (Image is presented in color)... 203

Figure 4.2. Thermal ellipsoid plot of {[C0(2,2'-bpy)2]3[F6(CN)6]2}+ (37)
at the 50 % probability level. The hydrogen atoms were
omitted for the sake of clarity (Image is presented in color). 204

l:‘iig‘tlre 4.3. A structural representation of the discrete cluster

{[Ni(2,2'-bPY)2(H20)][Ni(2,2'-be)2]3[Fe(CN )612} (38)
and space filling diagram (at right) taken from coordinates
of the X-ray structure (Image is presented in color) ....... 205

xxi

Figure 4.4. A structural representation of the anionic discrete cluster

{[Zn(phen)3][Zn(phen)2]2[Fe(CN)6]2} (39) Mid the space
filling model (at right) taken from coordinates of the X-ray
structure. (Image is presented in color) ...................... 206

Figure 4.5. A structural representation of {[Zn(phen)2][Fe(CN)6] }2
{[Zn(phen)2][Zn(phen)2(H20)][Fe(CN)6] }2 (40) taken from
coordinates of the X-ray structure. (Image is presented in

color) ............................................................. 207
Figure 4.6. SEM photograph of {[Co(2,2'-bpy)2]3[136((3Nklz}+ (37).. 213

Figure 4.7. (a) View of the 2-D network of {[MH(H20)2[MD(2,2'-
bpym)(H20)]2[Fe(CN)6]2} (36) down the b axis (b)
Scheme emphasizing the partial cube motif in the2-D
network(Image is presented in color) ....................... 233

Figure 4.8. A view along the c axis of {[Mn(H20)2[Mn(2,2'_
bem)(H20)]2[Fe(CN)6]2} (36) (Image in color) .......... 234

Figure 4.9. View of the {[Co(2,2'—bpy)2]3[Fe(CN),]2}+ (37) from the top
(left) and side (right) where the black rods represent CN' ligands
and each 2,2'-bpy ligand is represented by two blue atoms
attached to the cobalt atoms (Image is presented in color).. 238

Figure 4.10. Packing of the molecules in {[Co(2,2'-bpy)2]3[Fe(CN)g]2}+
(37) along the c axis (Image is presented in color) ...... 239

Figure 4.11. View of the packing diagram of {[Ni(2,2'-bpy)2(HzO)]
[Ni(2,2'-bpy)2]3[Fe(CN)6]2} (38) (a) along the ab plane and
(b) along the bc plane. (Image is presented in color)... 244

Figure 4.12. View of the packing diagram of {[Zn(phen)3][Zn(phen)2]2
[Fe(CN)6]2} (39) down the b axis. (Image is presented in
color) ........................................................... 248

Figure 4.13. Space filling diagram 0f {[Zn(phen)2][Fe(CN)6] }2

{[Zn(phen)2][Zn(phen)2(H20)][Fe(CN)6] }2 (40) taken
from coordinates of the X-ray structure. (Image is presented

in color) ........................................................ 251

xxii

Figure 4.14. Thermal dependence below 30 K of [m at 100 G for
complex (36). Inset: temperature dependence of 1/2'm
between 2—300 K. The solid line indicates the best fit
to the by Curie-Weiss law. Field dependence of the
magnetization at 2 K(bottom) .............................. 253

Figure 4.15. Temperature dependence of the ac susceptibility
(in-phase, x', and out-of-phase, x") below 13 K
(ac measuring field 1 G (104 T); frequency of 1 Hz;
no external dc field) .......................................... 254

xxiii

LIST OF COMPOUNDS

(1) ----------- [(2,2'-bpym)2Mn(OH2)2](BF4)2
(2) ---------- - [(2,2'-bpym)2Fe(OH2)2l(BF4)2
(3) ---------- — [(2.2'-bpym)2C0(OH2)2l(BF4)2
(4) ........... [(2,2'-bpym)2Ni(0H2)2](B 1302
(5) ........... [(2,2‘-bpy)2Mn(CH3CN)2](BF4)2
(6) ----------- [(2,2'-bpy)2Co(CH3CN)2](BF4)2
(7) ----------- [(2,2'-bpy)2Ni(CH3CN)2](BF4)2
(8) ----------- [(phen)2Ni(CH3CN)2](BF4)2
(9) - ---------- [(2,2'-bpy)2Ni(CH3CN)2](PF6)2
(10) --------- (2,2'-bpy)2Mn(CF3803)2
(11) --------- (2,2'-bPY)2Co(CF3803)2
(12) --------- (phen)2Mn(CF3S03)2
(13) --------- [(2,2'—be)2Ni(OH2)2](CF3SOg)2
(14) --------- (phen)2Mn(N03)2
(15) --------- (phen)2Co(N03)2
(16> -------- - (2,2'—bpy)2Mn(CN)2
(17) -----—--- (2,2'-bPY)2Co(CN)2
(18) -----—~~- [(4,4'-M62-2,2'—bpy)2CrC12]C1
(19) -----~——- [(4,4'-Mez-2,2'_bpy)2FeC12]Cl

xxiv

(20) --------- l(4,4'-M62-2,2'-bpy)2Fe(CN)2](P176)

(21) --------- [(4,4'-'Bu-2,2’-bpy)2Co(CN)2](PFg)

(22) --------- [TpFe(CH3CN)3](CF3SO3)

(23) --------- K[TpFe(CN)3]

(24) --------- [TpCo(CH3CN)3](BF4)

(25) --------- [TpCo(CH3CN)3](CF3SO3)

(26) --------- [TpCo(CH3CN)3](PF6)

(27) --------- [EulelTPC0(CN)3]

(28) --------- [TpNi(CH3CN)3](BF4)

(29) --------- [TpNi(CH3CN)3](CF3S03)

(30) --------- [TpNi(CH3CN)3](PF6)

(31) --------- NiTp2

(32) --------- [(9S3)Co(CH3CN)3](PF6)2

(33) --------- (9S3)CoCl2

(34) --------- [Co(9S3)2]C12

(35) --------- [FeTp21(BF4)

(36) --------- { Mn(H20)2[Mn(2,2'-bpym)(H20)]2[Fe(CN)6]2 }
(37) --------- { [C0(2,2'-bPY)2]3[Fe(CN)6]21+

(38) --------- { [Ni(2,2'-bPY)2(H20)] [Ni(2,2'-bPY)2]2[Fe(CN)6]2}
(39) --------- {[Zn(Phen)3][Zn(Phen)2]2[Fe(CN)6]2}

XXV

 

(40) --------
{ [Zn(phen)2][Fe(CN)6] }2{ [Zn(Phen)2(0H2)] [Zn(Phen)2] [Fe(CN)6] }2

xxvi

CH3CN

br
2,2'-bpy
2,2'-bpym

u

0C

dien
4,4'-Me2-2,2'-bpy

V

(PF6)’

IR

mmol

LIST OF ABBREVIATIONS

acetonitn'le

Angstrom

broad

2,2'-bipyridine
2,2'-bipyrimidine
bridging ligand, micro
Celsius
diethylenetriarnine
4,4'-dimethyl-2,2'-bipyridine
frequency

gram

halide
hexafluorophosphate
hour

infrared spectroscopy
medium intensity
milliliter

millimole

molarity (moles per liter)

xxvii

 

mol

N—N

(N03)-
NMR
(C104)
phen

[K- 1 8—C-6]
s

S
4,4'-‘Bu-2,2'-bpy
[Bu4N]
[13th
(13134)-
THF
((3133303)-
TP

983

cm'

mole

2,2'-bipyridine, 2,2'-bipyrimidine or
1 , 10-phenanthroline

nitrate
nuclear magnetic resonance
perchlorate
1 , 10-phenanthroline
potassium 18-C-6 ether
singlet, strong intensity
solvent molecule
4,4'-tert-butyl-2,2'-bipyridine
tetrabutylammonium
tetraethylammonium
tetrafluoroborate
tetrahydrofuran

triflate
tris(1-pyrazolyl)borohydride
1 ,4,7-tlithiacyclononane
wavelength

wavenumber

weak intensity

xxviii

Chapter 1

INTRODUCTION

INTRODUCTION
1. History of Molecular Magnetism

The use of soluble transition metal coordination complexes as
precursors to materials is a rapidly expanding area of inorganic chemistry
with many potential applications. Topological arguments that take into
consideration the geometrical preferences of the metals and ligands have
allowed chemists to design new molecule-based solids, including porous,1
magnetic,2 conducting3 and conducting materials that possess magnetic
centers.4

Molecular magnetism originated with the discovery of Wickman and
co—workers5 who reported that the complex FeCl(L-L)2 (L—L = N,N—
diethyldithiocarbamate) with an S = 3/2 ground state orders
ferromagnetically at a Tc of 2.5 K. Since then, the study of molecule-based
magnets has emerged as a new field, with notable breakthroughs by Kahn6
who reported the first inorganic-based molecular magnet ferrimagnetic chain
of Mn(II)Cu(II) centers and by Miller and co-workers,7 who discovered the
first organic based molecular magnet, [FeCp*2][TCNE]' (TCNE =
tetracyanoethylene). Since these developments, advancements in this field
include the discovery of high Tc ferromagnets based on the Prussian Blue

motif,8 spin-crossover compounds that undergo abrupt transitions near room

‘83.

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temperature,9 compounds that superconduct in the presence of localized
magnetic moments,10 and high spin clusters that mimic the properties of a
single domain magnet (single molecule magnets).ll

2. Prussian Blue

Among the more impressive magnetic solids based on coordination
compounds are those based on the three-dimensional, face-centered cubic
solid, [Fe4[Fe(CN)6]30xH20 (x = 14-16), called Prussian blue (PB), which
was discovered in 1704 by Diesbach, a Berlin artist.12 This material has been
used extensively in the manufacturing of paints, lacquers, printing inks,
laundry chalks and other color uses. The continued popularity of this
pigment is attributed to its low cost, deep bright shade, high color strength
and resistance to the action of water, organic media and acids.

An intriguing issue about PB that has fascinated chemists from the
beginning is that two virtually colorless ions, namely [Fe(HzO)6]3+ and
[Fe(CN)6]4”, react in water to produce an intensely colored blue precipitate.
It is now recognized that the color is due to a charge-transfer transition from
the Fe(II) to the Fe(II) ion through the cyanide bridge. The structure of PB
has also been the subject of great interest in the last century. The solid-state
structure consists of alternating ferrous and ferric metal ions at the corner of

a cubic lattice with edges of 5.1 Ana The cyanide groups lie along the edges

of the cubes connecting each metal atom. In spite of how long the material
has been known, the first single crystal X-ray study of Prussian Blue,
Fe4[Fe(CN)6]3-14HZO was not reported until 1977 by Ludi and co-
workers.13

As the previous paragraph alludes, there are two basic environments
for the metal centers in the Prussian Blue framework, assigned MA and MB
in the general formula MA,,[MB(CN)6]y.l4 The MA metals are coordinated to
the N atom of six cyanide ligands, creating a weak ligand field, whereas MB
metals are bound through the carbon atoms which creates a strong ligand
field. In the specific case of PB, Fe4[Fe(CN)6]3-xH20 (x = 14-16) (Figure
1.1.), the Fe(II) ions are coordinated to the carbon end of CN' and thus are
low—spin (16 ions whereas the Fe(III) ions are coordinated to the nitrogen end
of CN and are high-Spin (15 ions. This situation results in only one type of
paramagnetic site on PB, namely the LS. Fe(III) S=1/2 centers which
undergo ferromagnetic coupling through the diamagnetic Fe(II) centers. The
first indication of the ferromagnetic ordering at Tc = 5.5 K was detected by
Mossbauer spectroscopy.15’16 Later Mayoh and Day concluded that, in spite
of the long distances that separate the Fe"1 centers, the intervening FeII sites
participate in the magnetic interaction by providing a through bond-

pathway.17

A. Background Magnetic Properties
In order to understand the factors involved in molecular magnetism,’ 8
some basic magnetic phenomena must first be understood. In ferromagnets,
the individual spins are oriented in parallel fashion. In both antiferromagnets
and ferrimagnets, the spins are coupled antiparallel to each other. The
coupling constant J, describes the isotropic interaction between two spins $1
and S2, and is defined by the spin Hamiltonian H = -2J(S,oS2). The energy
separation between the singlet and the triplet states is J. For ferromagnetic
coupling, J > 0, while for antiferromagnetic coupling, J < 0, 1f the orbitals
containing the unpaired electron(s) are orthogonal to each other, then the
magnetic orbitals cannot interact and Hund’s rule keeps the spins parallel; in
this Situation, ferromagnetic coupling between the two spins occurs (Figure
1.2.). If direct overlap between the orbitals occurs as is the case when the
magnetic orbitals have the same symmetry, the antiparallel alignment Will be
favored. A type of ordering called ferrimagnetism occurs when the 100 a1
antiferromagnetically interacting spins are not of equal magnitude bur the

residual spins order in the same manner as a ferromagnet.

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3. Prussian Blue Analogues

Within the past ten years, researchers have opened up new venues for
Prussian-blue type chemistry by introducing a variety of metal atoms into
the cubic structure afforded by octahedral [M(CN)6]"' building blocks The
aim is to increase magnetic ordering temperatures, and, indeed, several
Prussian blue analogues have been prepared that exhibit 'I'c values above
room temperature.8 Prussian Blue analogues with metals other than iron are
currently playing a major role in the research of magnets that order at high
temperatures (Table 1.1.). An example of a Prussian Blue analogue is
Mn[Mn(CN)6]-l .14H20, which exhibits Curie paramagnetism between 140
and 300 K and a magnetic phase transition at 49 K due to ferrimagnetic
ordering of this mixed valence system.19 The MA site is occupied by high-
spin Mn(II) ions (t2g3eg2, SA = 5/2) whereas the MB site is occupied by
Mn(IV) ions 0233, SE = 3/2). The three unpaired electrons in the tzg QTbitaIs
are antiferromagnetically coupled, the net result of which is th at two

unpaired electrons from the Mn(II) centers are not cancelled. This magnetic

beElavior is dominated by the antiferromagnetic superexchange intefaCtion

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4. Controlled Syntheses of Specific Motifs

Nearly all of the d-block metals are known to form compounds of
cyanide in which the ligand exhibits different binding modes (Figure 1.3.). ‘4
Homoleptic and mixed ligand cyanide complexes with a wide range Of
oxidation states and coordination numbers ranging from two to eight are
known. The bidentate, linear nature of cyanide gives rise to extended
structures with 1-D, 2-D and 3-D motifs, the exact nature of which depends
on the coordination number and arrangement of ligands around the metal
centers.

One particular motif of interest in our laboratory is the molecular
square. Molecular squares composed of four metals bridged by four cyanides
have been known since the early 20th century, the most common of which is
based on square planar metal complexes with two cis protecting groups
(Figure 1.4.).20 Molecular squares can be prepared by a number of different
routes, but the one of interest in this thesis involves the self-assembly Offour

octahedral precursors each with two cis chelating ligands (N—N). There are
tWQ types of precursors, namely those that contain two cis cyanides in
addition to the two N-N ligands (donor positions) and those that contain
SolVent or leaving groups (acceptor Positions) as depicted in Figure 1.5. In a

reaction between precursors of this type, [(N-N)2M(CN)2]1n and

11

 

 

 

 

 

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Figure 13, Coordination modes Of the Cyanide ion.

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[(N-N)2M'(S)2]", the S ligands are displaced in favor of the nitrogen end of
the cyanide ligands with one potential outcome being a molecular square.
Molecular squares with octahedral 3d transition metal building blocks have
been prepared, but they are far less common than the square planar 4d and
5d metals.20d In terms of magnetic behavior, a homometallic square would
exhibit antiferromagnetic coupling, but by applying the orthogonality
principle as a guide in selecting metals for a heterometallic square,

ferromagnetic coupling can be favored.

In the vein of preparing open-shell molecular squares, Oshio and co-
workers reported [FezuCuZHQI-CN)4(bpy)6](PF6)402H2004CHC13 and
[Fe2mCuznw-CN)4(bpy)6](PF6)604CH3CN92CHC13 (Figure 1.6.)20i whose
magnetic properties are that of a simple paramagnet with noninteracting CuII
Centers in the FeZHCuZ" with low-spin Fe!I (S = O) and S = 1/2 CuII centers.
On the other hand, the FeszuzII square with two S = 1/2 FeIII centers in
addition to two S = 1/2 Cull centers exhibits ferromagnetic coupling between
the open shell Fe and Cu centers which gives rise to a total ground state for
the molecule of S = 2.

A logical extension of the molecular square family of compounds into
a third dimension is to molecular cubes, which have the potential for

possessing higher magnetic moments due to the presence of eight rather than

15

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only four metal centers. Molecular cubes were recently prepared
independently by Rauchfuss and Long, in which the corners consist of eight
metal atoms with bridging cyanides along the twelve edges. The remaining
three coordination sites on the metal centers are occupied by a facial capping
ligand, such as C5H5, C5Me5 or the triazacyclononane (tacn) ligand. In this
manner, Rauchfuss and co-workers prepared the molecular cube,
[(CP)4(C5(CH3)4(CH3CH2))4C04Rh4(CN)121(PF6)4 (Figure 1-7-), WhiCh
eKhibits interesting host-guest behavior.21 The molecule was characterized
by single crystal X-ray diffraction studies and found to have face diagonal
distances of 7.1 and 7.4 A with an interior volume estimated to be ~132 A3.
The covalent radii of the cube framework prohibit access to the interior since
Six CH3CN molecules are located near the cube faces, which are neither
bound to nor inserted into the cube.

In a more interesting example, the same research group demonstrated
the inclusion ability of [Et4N]3{M[(Cp*)Rh(CN)3]4[Mo(CO)3]4} (M = K, Cs)
(Figure 1.8.) with alkali metals.22 In the presence of an alkali metal cation,
these cubes form in solution from the reaction of (C6H3(CH3)3)Mo(CO)3 and
[Et4N][(Cp*)Rh(CN)3]. By replacing the Co(III) ion with the larger Mo(0)
atom, it was possible to obtain a much larger cube framework such that

alkali metal inclusion was possible. Competition experiments revealed that

17

the cube has a higher affinity for Cs+ than K+, thereby demonstrating the
feasibility for selective host-guest chemistry.

It is important to point out that performing Rauchfuss and co—workers

selected metals for their cube corners on the basis of size and relative

inertness with respect to substitution. The Co(III) Rh(III) and Mo(0)

ions/atoms used as cube comers are diamagnetic, which, of course,

precludes the molecules from having any magnetic properties. In contrast,
the work being conducted in our laboratories and those of Long and co-
workers is focused on the preparation of heterometallic cyanide cubes with
Paramagnetic transition metal centers.

The work of Long and co-workers has led to some key results in the
area, beginning with their report of the diamagnetic molecular cube,
[(tacn)gCog(CN)12](CF3SO3)12 (Figure 1.9.) which was structurally
characterized by single crystal X-ray diffraction methods.23 Although the
compound is not paramagnetic, it serves as a proof of concept that first row
transition metals can form such closed structures. The same group later

reported the reaction of [(tacn)Cr(HzO)3](CF3SO3)3 and [(tacn)Co(CN)3] to
yield the paramagnetic cube, [(tacn)3Cr4Co4(CN)12](CF3SO3)1208H20 which
was characterized by electrospray mass spectrometry. Unfortunately, no

Single crystals were obtained. Magnetic susceptibility measurements

18

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Figure 1.9. Thermal ellipsoid plot of the molecular cube structure [(tacn)3Cog(CN)12](O3SCF3)3 and a s
filling diagram.23

revealed a room temperature 11.,“ value of 7.51 B.M. with a g value of 1.97,
which is consistent with four isolated S = 3/2 Cr(III) centers per cube.
Evidently the diamagnetic Co(III) centers prevent coupling between the
Cr(III) centers.

Despite the lack of magnetic coupling exhibited by the compound
[(tacn)gCr4Co4(CN).2](O3SCF3)1208H20, it is important to continue to
prepare molecules of this type in order to test the possibility of having high
moments that lead to interesting magnetic behavior. Although the
Compounds are not cyanide-based, it is important to point out that several

Inixed-valence manganese oxide clusters24 (Figure 1.10.) with high ground

State spin values exhibit what is referred to as single molecule magnetism

(SMM). Unfortunately, it is not possible to predict the compositions or
magnetic superexchange of oxide clusters that form in aqueous solution due
to pH dependent redox reactions. In contrast, metal cyanide chemsitry is
under much more synthetic control, as evidenced by the results presented in
the aforementioned paragraphs.

Apart from the manganese oxide/carboxylate clusters, there are other
metal oxide molecules that exhibit the slow magnetic relaxation
characteristic of single molecule magnetism. A single molecule magnet

(SMM) is defined as a compound with discrete non-interacting molecules

22

that exhibit sufficiently large magnetic moments and axial magnetic
anisotropy (D) such that the molecule has an easy axis of alignment with an
external field with a barrier converting between the equal energy states of
magnetization parallel “T” to the field to magnetization antiparallel “i” to
the field. The presence of a thermal barrier to reorienting the magnetization
means that below a threshold temperature (the blocking temperature), the
molecules function as a magnetic switch. In response to an external
magnetic field, the magnetic moment of the SMM can be magnetized with
its spin either “up” or “down” along the axial magnetic anisotropy axis.
After the magnetic moment of this molecular species is oriented in an
external field, and when the external field is then removed, the moment of
the molecule will only very slowly reorient if the temperature is below the
“blocking temperature”. The key to making an SMM with an energy barrier
for the magnetic moment reversal that exhibits a slow relaxation is to build
in a ground state with high spin, S and negative axial magnetic anisotropy,
i. e., D < 0, since the barrier height for magnetization reversal scales as SZIDI.
A diagram of this double-well potential energy barrier for
[Mn]2012(02CCH3)16(H20)4]02(H02CCH3)04H20 (S = 10) is depicted in
Figure 1.11.24d Specifically for the Mn]; cluster, S = 10 and D = -O.50 cm’1

Which leads to a barrier height of ~50 cm‘l. At 2 K, the Mnlz complex has a

23

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magnetization relaxation half-life on the order of 2 months.

In order to explore the possibility of using such molecules as data
storage media, new clusters displaying larger values of S and D must be
prepared to significantly increase the barrier height for re-orienting the
magnetization of a particular molecule. In principle, a maximum of S = 10 is
possible with the eight metal atom molecular cube if the comers are

composed of alternating metal ions with electronic configurations of tZgB’eg0

2. As mentioned earlier, the orthogonality principle would dictate

and tzg‘seg
that all of the local unpaired spins in this molecule are ferromagnetically
coupled. In considering the parameters that lead to a thermal barrier to
reorienting the total magnetic moment of a molecule, one must consider the
shape of the cluster as well as single ion anisotropy. If the single ion values
are large and negative, viz, they exhibit -D values, the symmetrical
distribution of such ions in a molecule is likely to lead to a cancellation of
the effects of local anisotropy. So a restatement of the requirements for
increasing magnetic anisotropy can be rephrased to read “use metal atoms
with large negative single ion anisotropy (-D) and create molecular shapes
that are not highly symmetrica ”. Whether highly symmetrical molecular

cubes will exhibit single molecule magnetic behavior or not is still an open

question in the community. Since only a small number of single molecule

26

magnets are known it is not possible, at the present time, to predict how
high-spin transition metal cyanide cubes will behave.
5. Building Polymeric Assemblies and Clusters with
Hexacyanometallates

The spontaneous generation of well-defined architectures, for example
molecular squares or cubes, occur by self-assembly of molecular building
blocks with specific functionalities and geometries. Chapters 11 and III of
this dissertation describe the preparation of convergent precursors and their
reactions to form molecular squares and cubes. In Chapter IV an approach
that employs both convergent and divergent precursors is described. This
latter approach is based on the use of protecting groups on one metal center,
[(N-N)2M(S)2]“+, in reactions with hexacyanometallates, [M(CN)6]"‘. Okawa
and co-workers first reported the synthesis of a compound based on this
concept which is a 1-D rope ladder polymer from the reaction of
[Fem(CN)6]3' and trans-NinC12(en)2.2e The asymmetric unit of the structure
of [Ni"(en)2]3[Fem(CN)6]2 consists of two [Fem(CN)6]3‘ anions, two cis-
[Ni"(en)2]2+, one trans-[Ni"(en)2]2+ and two water molecules (Figure 1.12.).
These units produce polymeric zigzag chains by the connection of
[Fem(CN)6]3' and cis-[Ni"(en)2]2+ ions which are further stitched together by

the linkage trans-[Ni"(en)2]2+. The result is the existence of rope-ladder

27

chains that run along the c axis. The chains align along the diagonal line of
the ab plane to form 2-D sheets. The observation of the r.t. magnetic
moment of x,,,T = 4.95 cm3Kmol'1 for the magnetic unit FezNi3 coupled with
the fact that an abrupt increase of the moment occurs at a maximum at of T
= 14 K led the authors to conclude that a powdered sample (presumed to be
the same as the crystals) was an ordered magnet. Later, the researchers
published a series of crystallographically identical compounds,
[Ni"(en)2]3[Mm(CN)6]2-2H20 (MIII = Fe, Mn, Cr, and Co),25 which did not
exhibit magnetic ordering due to antiferromagnetic intermolecular
interactions between the pseudo 2-D sheets. The magnetic data for the first
sample was performed on a precipitate and not on crystals, but when the
crystals were finally measured, the compound was found to be metamagnetic
which means that the material switches from antiferromagnetic to
ferromagnetic coupling in the presence of a field. This study points out that
magnetic data must be obtained on crystalline samples, as powders may
have a different structure/composition or even degree of crystallinity
(disorder versus order) that can give rise to different magnetic properties.

In another example of chemistry related to this thesis work, Okawa
and co-workers synthesized the 2-D bimetallic assembly,

[Nin(pn)2]2[Fem(CN)6]ClO402H20 by combining [Fem(CN)(,]3' with

28

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[Niu(R,S-pn)2](ClO4)2 (pn = 1,2-diaminopropane) (Figure 1.13.).26 At r.t the
moment ”T is 3.21 cm3Kmol'l per FeNiz which increases with decreasing
temperature up to the maximum value at 9 K for the ferromagnetically
coupled FeNiz units.

In related work, a 3-D molecular ferrimagnet,
[Ni"(tren)]3[Fem(CN)6]2-6H20 (tren = tris(2-aminoethyl)amine), was
synthesized by Gatteschi and co-workers(Figure 1.14.).27, The magnetic

moment for the material is “T = 4.96 cm3Kmol'l at 225 K which is close to

the expected value for an uncoupled Ni3Fe2 unit. Further magnetic
measurements were obtained to characterize the magnetic ordering which
ultimately confirmed that a magnetically ordered state is achieved at 8 K.

In the previous cases, the dimensionality of the materials was either 1-
D or 2-D, but Okawa and co-workers have also prepared a 3-D bimetallic
ferrimagnet, namely [Mn(en)]3[Cr(CN)6]2-4H20 (en = ethylenediamine),
which exhibits a Tc = 69 K.28 This ordering temperature is the highest among
structurally characterized molecule-based magnets other than those in the
Prussian blue family. The crystal structure of the material reveals that all of
the cyanide groups of [Cr(CN)6]3' are involved in the coordination to
adjacent Mn2+ ions. Each Mn2+ ion is coordinated to one ethylenediamine

group and four cyanide nitrogen atoms from adjacent [Cr(CN)6]3‘ units

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32

 

(Figure 1.15.). The “T at room temperature is 13.08 cm3Kmol" per
Ml'l3Cl'2.

There are many more examples of polymeric arrays that have been
obtained by the aforementioned approach, but, more to the point of this
thesis, hexacyanometallate anions can also be used to yield discrete
structures as well. For example, Murray and co-workers reported the
pentanuclear cluster, [Ni“(bpm)2]3[Fem(CN)6]207H20 (bpm = Bis(1-
pyrazolyl)methane)) which the authors claim exhibits long range magnetic
ordering through hydrogen bonding.29 The cluster is composed of two
[Fem(CN)6]3' moieties in which three fac cyanides are connected to three
different [Ni"(bpm)2]2+ groups (Figure 1.16.). The geometry around the
nickel atoms is a cis arrangement. The three remaining CN’ ligands on 63011
Fe atom are monodentate, but are involved in hydrogen-bonding networks to
water molecules. The r.t. magnetic moment “T value is 5.12 cm3Kmol'l per
Ni3Fe2, with the signature of long-range magnetic ordering occurring at 23
K. Interestingly, there are two additional pentanuclear clusters that are said
to be structurally identical to the previously mentioned cluster but without
the network of hydrogen bonding. One is the pentanuclear cluster, [Ni(IM2-
py)2]3[Cr(CN)6]207H20 (IM2-py = 2-(2-pyridyl)-4,4,5,5-tetramethyl-4,5-

dihydro-lH-imidazolyl-l-oxy) with a S = 9 ground state.30 The compound

33

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35

was identified on the basis of elemental analysis, thermogravimetric
analysis, infrared and UV-visible spectroscopy, and magnetic data. No
crystal structure of the compound was obtained to confirm the proposed
structure. The pentanuclear Fe(III) analog, [Ni"(IM2-
py)2]3[Fem(CN)6]2-4H20, was also reported and exhibits a ground state of S
= 7 -3 1 At room temperature, “T is ~10 cm‘w’Kmol'l which corresponds to the
unit [Ni(IM2-py)2]3Fe2.

Chapter IV of the thesis describes the use of new octahedral
Precursors prepared in our laboratories that contain only leaving groups,
Clel'loted 8, namely [(N—N)2M(S)2]In and [(L3)M(S)3]n to build molecules with
briclging [M(CN)6]“' anions. This research led to the discovery of new
are11itectures with interesting magnetic properties, which will be described.
T‘lese compounds in this thesis add to our growing understanding of the
SYnthetic methodologies that one can use to prepare new molecular magnetic

materials based on cyanide linkages. These systems are of high interest for
their potential to exist with large ground spin state (S) values and large

molecular anisotropy.

36

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6. References

1. (a) Gardner, G. B.; Venkataraman, D.; Moore, J. S.; Lee, S. Nature 1995,
374, 792. (b) Venkataraman, D.; Gardner, G. B.; Lee, S.; Moore, J. S. J. Am.
Chem. Soc. 1995, 117, 11600. (c) Yaghi, O. M.; Li, H. J. Am. Chem. Soc.
1995, 117, 10401.

2. (a) Manriquez, J. M.; Yee, G. T.; McLean, S.; Epstein, A. J.; Miller, J. S.
Science 1991, 252, 1415. (b) Tamaki, H.; Zhuang, Z. J.; Matsumoto, N.;
Kida, S.; Koikawa, M.; Achiwa, Hashimoto, Y.; Okawa, H. J. Am. Chem.
Soc. 1992, 114, 6974. (c) Stumpf, H. 0.; Pei, Y.; Kahn, 0.; Sletten, J.;
Renard, J. P. J. Am. Chem. Soc. 1993, 115, 6738. (d) Inoue, K.; Iwamura, H.
J. Am. Chem. Soc. 1994, 116, 3173. (e) Ohba, M.; Maruono, N.; Okawa, H.;
Enoki, T.; Latour, J.-M. J. Am. Chem Soc. 1994, 116, 11566. (1) Decurtins,
89; Schmalle, H. W.; Schneuwly, P.; Zheng, Li-M.; Ensling, J.; Hauser, A.
Inorg. Chem. 1995,34, 5501. (g) Miyasaka, H.; Matsumoto, N.; Okawa, H.;
Re, N.; Gallo, B.; Floriani, C. Angew. Chem. Int. Ed. Engl. 1995, 34, 1446.
(h) Ohba, M.; Okawa, H.; Ito, T.; Ohto, A. J. Chem. Soc. Chem. Commun.
1995, 1545. (i) Michaut, C.; Ouahab, L.; Bergerat, P.; Kahn, 0.; Bosseksou,
A. J. Am Chem. Soc. 1996, 118, 3610. (j) De Munno, G.; Poerio, T.; Viau,

G.; Julve, M.; Lloret, F.; Joumaux, Y.; Riviere, E. J. Chem. Soc, Chem.

Commun. 1996, 2587.

39

3. (a) Bechgaard, K.; Cameiro, K.; Rasmussen, F. B.; Olsen, M. J. Am.
Chem. Soc. 1981, 103, 2440. (b) Wudl, F. Acc. Chem. Res. 1984, 17, 227. (c)
Lacroix, P.; Kahn., 0.; Gliezes, A.; Valade, L.; Cassoux, P. Nouv. J. de
Chimie 1985, 643. ((1) Gross, R.; Kaim, W. Angew. Chem. Int. Ed. Engl.
1987, 26, 251. (e) Ballester, L.; Barral, M.; Gutierrez, A.; Jiménez-Aparicio,
R. ; Martinez-Muyo, J .; Perpifian, M.; Monge, M.; Ruiz-Valero, C. J. Chem.
Soc.,Chem. Commun. 1991, 1396. (f) Humphrey, D. G.; Fallon, G. D.;
Murray, K. S. J. Chem. Soc., Chem. Commun. 1988, 1356. (g) Comelissen,
J- P.; Van Diemen, J. H.; Groeneveld, L. R.; Haasnoot, J. G.; Spek, A. L.;
R€=€3dijlg J. Inorg. Chem. 1992, 31, 198. (h) Oshio, H.; Ino, B.; Mogi, 1.; Ito,
T~ Inorg. Chem. 1993, 32, 5697. (i) Ballester, L.; Barral, M.; Gutierrez, A.;
MQnge, A.; Perpifian, M. F.; Ruiz-Valero, C.; Sénchez-Pélaez, A. Inorg.
Chem. 1994, 33, 2142. (j) Oshio, H.; Ino, B.; Ito, T.; Maeda, Y. Bull. Chem.
SOC. Jpn. 1995, 68, 889. (k) Azcondo, M. T.; Ballester, L.; Gutierrez, A.;
Perpifian, F.; Amador, U.; Ruiz-Valero, C.; Bellitto, C. J. Chem. Soc.,
Dalton Trans. 1996, 3015.
4. Aumiiller, A.; Erk, P.; Klebe, G.; Hiinig, 8.; Von Schiitz, J.; Werner, H.
Angew. Chem. Int. Ed. Engl. 1986, 25, 740. (b) Aumijller, A.; Erk, P.;
Hiinig, S. Mol. Cryst. Liq. Cryst. Inc. Nonlinear. Opt. 1988, 156, 215. (c)

Erk, P.; Gross, H.-J.; Hiinig, U. L.; Meixner, H.; Werner, H.-P.; Von Schiitz,

40

I. U.; Wolf, H. C. Angew. Chem. Int. Ed. Engl. 1989, 28, 1245. (d) Kato, R.;
Kobayashi, H.; Kobayashi, A. J. Am. Chem. Soc. 1989, 111, 5224. (e)
Aumiiller, A.; Erk, P.; Hiinig, S.; Héidicke. B.; Peters, K.; Von Schnering, H.
G. Chem. Ber. 1991, 124, 2001. (f) Sinzger, K.; Hiinig, S.; Jopp, M.; Bauer,
D. ; Bietsch, W.; Von Schlitz, J. U.; Wolf, H. C.; Kremer, R. K.; Metzenthin,
T; Bau, R.; Khan, S. I.; Lindbaum, A.; Lengauer, C. L.; Tillmanns, E. J.
Am. Chem. Soc. 1993, 115, 7696. (g) Gomez-Garcia, C. J.; Gimenez-Saiz,
C; Triki, S.; Coronado, E.; Magueres, P. L.; Ouahab, L.; Ducasse, L.;
Sourisseau, C.; Delhaes, P. Inorg. Chem. 1995, 34, 4139. (h) Day, P.;
Kat—moo, M. J. Mat. Chem. 1997, 7, 1291. (i) Clemente-Leon, M.;
Mil—lgotaud, C.; Agricole, B.; Gomez-Garcia, C.; Coronado, E.; Delhaes, P.
Aug ew. Chem. Int. Ed. Engl. 1997,36, 1114. (j) Canfield, P. C.; Gammel, P.
L; Bishop, D. J. Physics Today 1998, 40. (k) Petruska, M. A.; Talham, D. R.
Chem. Mater. 1998, 10, 3672.

5 C a) Wickman, H. H.; Trozzolo, A. M.; Williams, H. J.; Hull, G. W.;

Met‘Iitt, F. R. The Physical Review 1967, 155, 563. (b) DeFotis, G. C.;

Palacio, F.; O’Connor, C. J.; Bhatia, S. N.; Carling, R. L. J. Am. Chem. Soc.

1977, 99, 8314.

41

6. Pei, Y.; Kahn, 0.; Nakatani, K.; Codjovi, E.; Mathoniere, C.; Sletten, J. J.
Am- Chem. Soc. 1991, 113, 6558. (b) Pei, Y.; Veraguer, M.; Sletten, J.;
Renard, J. P. J. Am. Chem. Soc. 1986, 108, 7428.

7. Miller, J. S.; Calabresse, J. C.; Epstein, A. J .; Bigelow, W.; Zhang, J. H.;
Reiff, W. M. J. Chem. Soc., Chem. Commun. 1986, 1026.

8. (a) Gadet, V.; Mallah, T.; Castro, 1.; Berdaguer, M. J. Am. Chem. Soc.
1992, 114, 9213. (b) Verdaguer, M. Science 1996, 272, 698, and references
therein. (c) Bushmann, W. E.; Paulson, S. C.; Wynn, C. M.; Girtu, M. A.;
Epstein, A. J.; White, H. S.; Miller, J. S. Chem. Mat. 1998, 10, 1386. ((1)

Perl ay, 8.; Mallah, T.; Ouachés, R.; Veillet, R.; Verdaguer, M. Inorg. Chem.

1999, 38, 229.

O

9- (a) Miller, J. 8.; Epstein, A. J.; Chem. Commun. 1998, 1319. (b) Zhang, 1.,
Liable-Sands, L. M.; Rheingold, A. L.; Del Sesto, R. E.; Gordon, D. C.;
Burl-(hart, B. M.; Miller, J. 8. Chem. Commun. 1998, 1385. (c) Zhang, J.;
Ensling, J .; Ksenofontov, V.; Giitlich, P.; Epstein, A. J .; Miller, J. S. Angew.
Chem. 1m. Ed. 1998, 37, 637.
10' (a) Kurmoo, M.; Graham, A. W.; Day, P.; Coles, S. J.; Hursthouse, M.
3'3 Caulfield, J. L.; Singleeton, J.; Pratt, S. J.; Hayes, W.; Ducasse, L.;

Guionneau, P. J. Am. Chem. Soc. 1995, 117, 12209. (b) Martin, L.; Turner,

42

S. 8.; Day, P. Chem. Commun. 1997, 1367. (c) Day, P. Physica Scripta
1993, T49, 726.

1 1 - (a) Caneschi, A.; Gatteschi, D.; Sessoli, R. J. Am. Chem. Soc. 1991, 113,
5873. (b) Sessoli, R.; Tsai, H. L.; Schake, A. R.; Wang, 8.; Vincent, J. B.;
Folting, K.; Gatteschi, D.; Christou, G.; Hendrickson, D. N. J. Am. Chem.
Soc- 1993, 115, 1804. (c) Sessoli, R.; Gatteschi, D.; Caneschi, A.; Novak, M.
A- [Vature 1993, 365, 141. (d) Abbati, G. L.; Comia, A.; Fabretti, A. C.;
Carleschi, A.; Gatteschi, D. Inorg. Chem. 1998, 37, 3759. (e) Abbati, G. L.;
Coma, A.; Fabretti, A. C.; Caneschi, A.; Gatteschi, D. Inorg. Chem. 1998,
37, 1430. (f) Schmid, G. J. Chem. Soc., Dalton Trans. 1998, 1077. (g)
317% chin, E. K.; Clegg, W.; Murrie, M.; Parsons, S.; Teat, S. J.; Winpenny,
R- E. P. J. Am. Chem. Soc. 1998, 120, 7365. (h) Miiller, A.; Krickemeyer,
E- ; IBdgge, H.; Schmidtmann, M.; Beugholt, C.; Kdgerler, P.; Lu, C. Angew.
Chem. Int. Ed. Engl. 1998,37, 1220. (i) Watton, s. P.; Fuhrrnann, P.; Pence,
L- 13.; Caneschi, A.; Comia, A.; Abbati, G. L.; Lippard, s. J. Angew. Chem.
Int- Ed. Engl. 1997,36, 2774. (i) Tran, N. T.; Kawano, M.; Powell, D. R.;
Dahl, L. F. J. Am. Chem. Soc. 1998, 120, 10986. (k) Miiller, A.; Shah, S.Q.

“‘3 Bfigge, H.; Schmidtmann, M. Nature 1999, 397, 48.

\1- (a) Keggin, J. F.; Miles, F. D. Nature 1936, 137, 577. (b) Holtzman, H.

Ind. Eng. Chem. 1945, 37, 855. (c) El-Sayed, M. F. A.; Sheline, R. K. J.

43

Inorg. Nucl. Chem. 1958, 6, 187. (d) Dows, D. A.; Haim, A.; Wilmarth, W.
K- J. Inorg. Nucl. Chem, 1961, 21, 33. (e) Griffith, W. P. Q. Rev., 1962, I6,
188- (t) Shriver, D. F. Structure Bonding, 1966, 32. (g) Chadwick, B. M.;
Sharpe, A. G. In Advances in Inorganic Chemistry and Radiochemistry
1966, 8, 83. (h) Britton, D. In Perspectives in Structural Chemistry 1967, I,
109- (i) Ludi, A.; Gudel, H. U. Structure Bonding, 1973, 14, 1.
l3 .. (a) Buser, J. H.; Ludi, A. J. Chem. Soc. Chem. Commun., 1972, 1299. (b)
Bu ser, H. J.; Schwarzenbach, D.; Petter, W.; Ludi, A. Inorg. Chem. 1977,
15, 2704.
14- - (a) Sharpe, A. G. The Chemistry of Cyano Complexes of the Transition
Metals, Academic Press Inc. New York 1976. (b) Dunbar, K. R.; Heintz, R.
A- Irogress in Inorg. Chem. 1997, 45, 283. (c) Vahrenkamp, H.; Geiss, A.;
Richardson, G. N. J. Chem. Soc. Dalton, 1997,20, 3643.

15 - Ito, A.; Suenaga, M.; Ono, K. J. Chem. Phys, 1968, 48(8), 3597.

15- Chappert, J.; Sawicka, B.; Sawicki, J. Phys. Stat. Sol, 1975, B72, K139.
17' Mayoh, B.; Day, J. J. Chem. Soc. Dalton Trans, 1976, 1483.

18‘ (a) Kahn, 0. Molecular Magnetism, VCH, Weinheim, 1993. (b) Carlin,

R' L. Magnetochemistry, Springer-Verlag Berlin Heidelberg, 1986. (c)

BEthel, D. Comments Inorg. Chem, 1986, 5(6), 2.

X9. Klenze, R.; Kanellakoupuolos, B.; Trageser, G.; Eysel, H. H. J. Chem

Phys, 1980, 72(11), 5819.
20- (a) Phillips, R. F.; Powell, H. M. Proc. R. Soc. London 1993, 173, 147.

(b) Shaw, B. L.; Shaw, G. J. Chem. Soc. A. 1971, 3533. (c) Slone, R. V.;
Hupp, J. T.; Stern, L. C.; Albretch-Schmidt, T. E. Inorg. Chem 1996, 35,
4096. (d) Stang, P. J.; Olenyuk, B. Acc. Chem. Res. 1997, 30, 502. (e)
Olenyuk, B.; Fechtenkotter, A.; Stang, P. J. J. Chem. Soc. Dalton Trans.
1998, 1707. (f) Hupp, J. T. Coord. Chem. Rev. 1998, I71, 221. (g)
Benkstein, K. D.; Hupp, J. T.; Stern, L. C. Inorg. Chem. 1998, 37, 5404 (h)
Woessner, S. M.; Helms, J. B.; Shen, Y.; Sullivan, B. P. Inorg. Chem. 1998,
37, 5406. (i) Oshio, H.; Tamada, 0.; Onodera, H.; Ito, T.; Ikomo, T.; Tero-
Kubota, S. Inorg. Chem. 1999, 38, 5686.

21 - Klausmeyer, K. K.; Rauchfuss, T. B.; Wilson, S. R. Angew. Chem. Int.

Ed. Engl. 1998, 37, 1694.
22- Klausmeyer, K. L.; Wilson, S. R.; Rauchfuss, T. B. J. Am. Chem. Soc.
1999, 121, 2705.
23 ° I*leinrich, J. L.; Berseth, P. A.; Long, J. R. Chem. Commun. 1998, 1231.
24- (a) Friedman, J. R.; Sarachik, M. P.; Tejada, J.; Ziolo, R. Phys. Rev. Lett.
1996, 76, 3830. (b) Thomas, L.; Lionti, F.; Ballou, R.; Gatteschi, D.; Sessoli,
R3. Barbara, B. Nature 1996, 383, 145. (c) Aubin, S. M. J .; Wemple, M. W.;

Adams, D. M.; Tsai, H. L.; Christou, G.; Hendrickson, D. N. J. Am. Chem.

45

Soc. 1996, 118, 7746. (d) Aubin, S. M. J .; Spagna, S.; Eppley, H. J .; Sager,
R- B.; Folting, K.; Christou, G.; Hendrickson, D. N. Mol. Cryst. and Liq.
Cryst. Science and Tech. Sec. A.-Mol. Cryst. Liq. Cryst. 1997, 305, 181. (e)
Aromi, G.; Aubin, S. M. J.; Spagna, S.; Bolcar, M. A.; Eppley, H. J.;
Folting, K.; Christou, G.; Hendrickson, D. N.; Huffman, J. C.; Squire, R. C.;
Ts ai, H. L.; Wang, S.; Wemple, M. W. Polyhedron 1998, 17, 3005. (f) Ruiz,
D- ; Sun, Z.; Albela, B.; Folting, K.; Ribas, J .; Christou, G.; Hendrickson, D.
N- Angew. Chem. Int. Ed. Engl. 1998, 37, 300.

25 - Ohba, M.; Okawa, H. Coord. Chem. Rev. 2000, 198, 313.

25 - Ohba, M.; Okawa, H.; Ito, T.; Ohto, A. J. Chem. Soc., Chem. Commun.
1995, 1545.

27 - Salah, M.; Fallah, E.; Rentschler, E.; Caneschi, A.; Sessoli, R.;
Gatteschi, D. Angew. Chem. Int. Ed. Engl. 1996, 35, 1947.

28 - Ohba, M.; Usuki, N.; Fukita, N.; Okawa, H. Angew. Chem. Int. Ed.Engl.
1999, 38, 1795.

29‘ Langenberg, K. V.; Batten, S. R.; Berry, K. J.; Hockless, D. C. R.;

MO‘-113araki,B.; Murray, K. s. Inorg. Chem. 1997,36, 5006.

30' Marvilliers, A.; Pei, Y.; Boquera, J. C.; Vostrikova, K. E.; Paulsen, C.;

Riviere, B.; Audiere, J.-P.; Mallah, T. Chem. Commun. 1999, 1951.

46

 

 

3 l . Vostrikova, K. E.; Luneau, D.; Wemsdorfer, W.; Rey, P.; Verdaguer, M.
J. Am. Chem. Soc. 2000, 122, 718.
32- (a) Holmes, S. M.; Girolami, G. S. J. Am. Chem. Soc. 1999, 121, 5593.
Ch) I-Iatlevik, 0.; Buschmann, W. B.; Zhang, J .; Manson, J. L.; Miller, J. S.
Adv. Mater. 1999, 11, 914. (c) Dujardin, E.; Ferlay, S.; Phan, X.;
De splances, C.; d. Moulin, C. C.; Sainctavit, P.; Baudelet, F.; Dartyge, E.;
Veillet, P., Verdaguer, M. J. Am. Chem. Soc. 1998, 120, 11347. (d) Ferlay,
S. ; Mallah, T.; Ouahes, R.; Veillet, P.; Verdaguer, M. Nature (London),
1995, 378, 701. (e) Mallah, T.; Thiébaut, S.; Verdaguer, M.; Veillet, P.
Seience 1993, 262, 1554. (f) Entley, W. R.; Girolami, G. S. Science 1995,
258, 397. (g) Babel, D. Comments Inorg. Chem. 1986, 5( 6), 285., Greibler,
W- D.; Babel, D. Z Naturforsch. 1982, 87b, 832. (h) Entley, W. R.;
Gi r—«olami, G. s. Inorg. Chem. 1994, 33, 5165. (i) Juszczyk, S.; Johansson,
C- 3 Hanson, M.; Ratuszna, A.; Malecki, G. J. Phys. : Condens. Matter 1994,
6, S 697.

33 ' (a) Zhong, Z. J .; Seino, H.; Mizobe, Y.; Hidai, M.; Verdaaguer, M.;
Ohkoski, S.-I.; Hashimoto, K. Inorg. Chem. 2000, 39, 5095. (b) Larionova,
19» Kahn, o.; Gohlen, S.; Ouahab, L.; Clérac, R. J. Am. Chem. Soc. 1999,
12 1 , 3349. (c) Ohba, M.; Okawa, H.; Fukita, N.; Hashimoto, Y. J. Am.

Chem. Soc. 1997, 119, 1011. (d) Ohba, M.; Okawa, H.; Ito, T.; Ohto, A. J.

47

Chem Soc., Chem. Commun. 1995, 1545. (e) Kou, H.-Z.; Gao, S.; Ma, B.-
Q-; Liao, D.-Z. Chem Commun. 2000, 1309. (t) Kou, H.-Z.; Gao, S.; Bu,
W--M.; Liao, D.-Z.; Ma, B.—Q.; Jiang, Z.-H.; Yan, S.-P.; Fan, Y.-G.; Wang,
G- -L. J. Chem. Soc., Dalton Trans. 1999, 15, 2477. (g) Sra, A. K.; Andruh,
NI - ; Kahn, 0.; Golhen, S.; Ouahab, L.; Yakhmi, J. V. Angew. Chem. Int. Ed.
1999, 38, 2606. (h) Re, N.; Gallo, E.; Floriani, C.; Miyasaka, H.;

Matsumoto, N. Inorg. Chem. 1996, 35 , 6004.

48

Chapter 11
Synthesis, Characterization and Reactivity Studies of
Square Precursors of the Type cis-[(N-N);M(S)2]"+

(5 = H209 (CFJSOJa CH3CN9 (N 03)-, (CND

49

l - INTRODUCTION
Many magnetic materials, most notably the three dimensional Prussian blue
(3 mbic solids depicted in Figure 1.1, are based on the cyanide ligand due to its
effectiveness for providing an efficient pathway for magnetic
communication between paramagnetic metal centers'. The prototype for the
field is Prussian blue, Fe4[Fe(CN)6]3.tzO (x = 14-16), which contains Fe11

in metal centers bridged by cyanidez. The strong field, carbon end, of

and Fe
CN’ is bound to FeII which is low-spin, and the weak-field, nitrogen end, is
bound to FeIII which is high-spin (S = 5/2). The physical properties of
Prussian blue have been under investigation for many decades, and it is now
\widely recognized that the mixed-valency is responsible for the intense blue
Color of the solid as well as for the observed ferromagnetic ordering at 5.5
R3. Within the past ten years, researchers have opened up new venues for
Prussian-blue type chemistry by introducing a variety of metal atoms into
the cubic structure afforded by octahedral [M(CN)6]“' building blocks. The
aim is to increase the magnetic ordering temperature, and, indeed, several
Prussian blue analogs have been observed to have Tc values above room
temperature (Table 1.1.).4 Unfortunately, the characterization and general

I-lsefulness of the PB solids is severely hampered by their total lack of

SOlubility, thus researchers are seeking new ways to apply cyanide chemistry

50

to magnetism.

A completely different approach to cyanide chemistry from that
mentioned above is to reduce the dimensionality by using capping ligands to
avoid the growth of a three dimensional network. Okawa and co-workers
were the first group to apply this strategy by using ethylenediamine ligands

in combination with hexacyanometallates to form l-D chains, 2-D layers and
3-D motifs.5 It is possible to use capping ligands to further lower the
dimensionality to favor discrete molecules such as the first documented
tetranuclear cyanide-based cluster [{closo-3-PPh3-3 (u-CN)—3, l ,2-
IthzBoth] reported by Hawthorne and co-workers“. This molecule
consists of four closo phosphinorhodacarborane moieties joined through
their respective metal centers by linear cyanide bridges to give a cyclic
structure. Another example, provided by Maitlis and co-workers, is the
cluster [{(C5(CH3)5Rh-u-CH2)2}2(u-CN)2](PF6)2 composed of two

{(C5(CH3)5Rh-u-CH2)2} units bridged by two cyanide ligands.7 Additional
examples of organometallic molecular squares, and even triangles, have
emerged in recent years“, but there are no examples of paramagnetic cyanide
Squares with two exceptions. During the course of our studies, Oshio and co-

workers9 reported [FenzCu“2(u-CN)4(bpy)6](PF6)4.2HZO.4CHCl3 and

[FemZCu"2(u-CN)4(bpy)6](PF6)6o4CH3CNo2CHC 13 with Cu(II) and Fe(III)

51

paramagnetic metal centers. Magnetic susceptibility studies revealed that the
F enzCunz square based on low-spin FeII and S = '/2 Cu‘I ions is a simple
paramagnet with noninteracting CuII centers. The FemZCunz square with two
S = V2 FeIII centers in addition to two S = 1/2 Cu11 centers exhibits
ferromagnetic coupling which gives rise to a ground state of S = 2.
In order to design a convergent synthesis of molecular squares fi'om
octahedral metal ions, one must cap four coordination sites with two cis
chelating ligands or use a tetradentate ligand that leaves two cis sites open
for substitution chemistry. These compounds, then, will have an angle of 90°
between the labile sites as displayed in Figure 2.1. Inexpensive choices for
bidentate capping ligands are 2,2'-bipyridine or 1,10-phenanthroline which,
because of the steric hindrance afforded by the opposing hydrogen atoms,
Bind exclusively as cis ligands. The other building block can be a precursor
also tailored to have four sites blocked by innocent capping ligands but, in
this case, the other two sites are occupied by cyanide ligands at 90°. One can
envisage that the reaction between cis-[(N-N)2M(S)2]n+ and cis-[(N-N);
M'(CN)2] can yield either a molecular square (Figure 2.2.) or a one-
dimensional zigzag chain, depending on kinetic versus thermodynamic
Control. In this chapter, the preparation and characterization of the two this

different types of precursors are presented and discussed.

52

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54

2. EXPERIMENTAL
A. PHYSICAL METHODS
I nfrared spectra were recorded on a Nicolet 42 spectrophotometer either in
the Chemistry Department at Michigan State University or on a Nicolet 470
instrument in the Chemistry Department at Texas A&M University. Infrared

' resolution and 32 scans unless otherwise

spectra were recorded at 4 cm‘
stated. Solid samples were measured as KBr pellets or Nujol mulls on KBr
or CsI plates. Elemental analyses were performed at Desert Analytics,
"Tucson, AZ or in the chemistry department at Michigan State University
Vvith a Perkin and Elmer Series II CHNS/O analyzer 2400. Magnetic
measurements were performed on a Quantum Design MPMS-S equipped
Vvith a SQUID sensor housed in the Physics and Astronomy Department at
Michigan State University or a MPMS-XL SQUID magnetometer located in
the Chemistry Department at Texas A&M University.

13. SYNTHESES

The starting materials MCl3 (M = Cr, Fe) and MClz, (M = Mn, Fe, C, Ni)
and their analogous hydrates were purchased from Aldrich Chemical
Company and used without further purification. FeC 12 was prepared by

literature methods.10 The ligand 4,4'-dimethyl-2,2'-bipyridine was purchased

from Aldrich and used without further purification. The ligands 2,2'-

55

bipyridine and 1,10-phenanthroline were purchased from Fisher or Aldrich
and recrystallized before use. The ligand 2,2'-bipyrimidine was prepared
according to published methods or a slight modification thereof.ll The
ligand 4,4'-‘Bu-2,2'-bpy was prepared according to published methods or a
slight modification thereof.‘2 Thallium hexafluorophosphate, silver
tetrafluoroborate, silver nitrate and silver triflate were purchased from either
Strem or Aldrich and used without further purification. The starting material,
(THF)3CrCl3, was prepared according to literature methods.l3 Acetone and
acetonitrile were distilled over 3 A sieves, whereas benzene, diethyl ether,
'THF and toluene were distilled over sodium-potassium/benzophenone.
Methylene chloride was distilled over P205 under a nitrogen atmosphere
whereas methanol and ethanol were dried using magnesium alkoxide. Unless
otherwise specified, all reactions were carried out under a nitrogen
atmosphere using standard Schlenk-line techniques.
(1) [(2.2'-bpym)2M(0Hml(BFm (M = Mn"(1), Fe“(2). Co"(3), Ni"(4».
Preparation of [(2,2'-bpym)2Mn(OH2)z](BF4)2 (l).
A quantity of AgBF; (0.698 g, 3.59 mmol) in 40 mL of acetonitrile was
added via cannula techniques to (2,2'-bpym)2MnC1202HzO (0.856 g, 1.79
mmol) in 40 mL of acetonitrile.14 An immediate white precipitate of AgCl

fOrmed, which was separated from the yellow solution by filtration through

56

 

Celite and centrifugation. The volume of solution was reduced to ~5-10 mL,
and 40 mL of diethyl ether were added to precipitate a pale yellow solid. The
diethyl ether was removed by cannula techniques, and the yellow solid was
dried in vacuo. Slow evaporation in air yielded crystals. (0.108 g, 10%) IR
(KBr pellet, cm"): 1574 (s), 1493 (m), 1452 (m), 1408 (s), 1300 (m), 1242
(w), 1217 (w), 1084 (s, br), 823 (m), 756 (s), 696 (m), 667 (m), 657 (m), 534
(m), 522 (m), 265 (m), 240 (m).
Preparation of [(2,2'-bpym)2Fe(OH2)z](BF4)2 (2).
'The reagent AgBF4 (0.952 g, 4.89 mmol) dissolved in 40 mL of acetonitrile
was added via cannula techniques to a 40 mL acetonitrile solution of (2,2'-
bpym); FeC12 (1.08 g, 2.44 mmol). The AgCl by—product was removed by
filtration through Celite and collected by centrifugation. The red filtrate was
reduced in volume to 5-10 mL and treated with 40 mL of diethyl ether. A
red solid was separated from the acetonitrile/ diethyl ether solution by
cannula techniques and dried in vacuo. Yield: (0.306 g, 22%). IR data (KBr
pellet, cm‘l): 3443 (8, br), 3082 (w), 3026 (w), 2924 (m), 2853 (w), 1628
(w), 1577 (s), 1556 (m), 1493 (m), 1457 (m), 1406 (s), 1300 (m), 1084 (8,
br), 819 (m), 788(w), 754 (s), 696(8), 659 (m), 534 (m), 523 (m).

Preparation of [(2,2'-bpym)2Co(OH2)2](BF4)z (3).

57

An acetonitrile solution (40 mL) of AgBF; (0.597 g, 3.07 mmol) was added
dropwise to a 40 mL acetonitrile solution of (2,2'-bpym)2CoC1203HzO (0.762
g, 1.53 mmol)" The AgCl was removed from an orange solution by
filtration through Celite and centrifugation. The orange filtrate was reduced
to ~5-10 mL and treated with 40 mL of diethyl ether to yield an orange
solid. The diethyl ether was removed by cannula techniques, and the orange
solid was dried in vacuo. Yield: (0.129 g, 15%) IR data (KBr pellet and C81
plates with Nujol (2 cm'1 resolution), cm"): 3084 (w), 3026 (w), 2963 (w),
2922 (w), 1631 (w), 1576 (s), 1558 (s), 1452 (w), 1408 (s), 1261 (m), 1211
(w), 1084 (8, br), 819 (m). 760 (s), 698 (m), 688 (m), 675 (w), 659 (m), 534
(m), 523 (m), 428 (w), 396 (w, br), 303 (w), 288 (m), 265 (m), 228 (w), 216
(w), 209 (w), 203 (w).

Preparation of [(2,2'-hpym)2Ni(OH2)2](BF4)2 (4).

An acetonitrile solution (40 mL) of AgBF; (0.731 g, 3.76 mmol) was added
via cannula techniques to a 40 mL acetonitrile solution of (2,2'-
bpym)2NiC1203HzO (0.871 g, 1.88 mmol).14 The AgCl was removed fiom a
pale-pink solution by filtration through Celite and centrifugation. The
volume of solution was reduced to ~5-10 mL, and 40 mL of diethyl ether
was added to precipitate a pale pink solid. The diethyl ether was removed by

cannula techniques, and the pink solid was dried in vacuo. Yield: (0.370 g,

58

34%). IR data (KBr pellet, cm"): 3084 (w), 3026 (w), 2963 (w), 2924 (w),
1632 (w), 1577 (s), 1560 (s), 1452 (m), 1408 (s), 1300 (w), 1261 (m), 1084
(8, br), 819 (m), 758 (s), 696 (m), 690 (m), 679 (w), 661 (m), 534 (m), 523
(m).

(2) [(2,2'-bpy)2M(CH3CN)2](BF4)2 for M = Mn"(5), Co“(6) and Ni“(7).
Preparation of [(2,2'-bpy)2Mn(CH3CN)2](BF4)2 (5).

A sample of AgBF4 (1.31 g, 6.76 mmol) dissolved in 40 mL acetonitrile was
added via cannula techniques to a 40 mL acetonitrile of (2,2'-
bpy)2MnC12-2HZO (1.60 g, 3.37 mmol). The AgCl was removed by passing
the pale yellow solution through Celite. The volume of solution was reduced
to ~5-10 mL, and 40 mL of diethyl ether were added to induce precipitation
of a pale yellow solid. The diethyl ether was removed by cannula
techniques, and the yellow solid was dried in vacuo. Yield: (1.803 g, 86%)
IR data (CsI plates with Nujol, em"): 3508 (m), 2312 (s), 2285 (s), 1650
(m), 1599 (s), 1577(8), 1495 (m), 1441 (s), 1365 (m), 1319 (m), 1286 (m),
1248 (m), 1221 (w), 1064 (8, br), 769 (s), 738 (m), 652 (m), 625 (m), 579
(w), 550 (w), 521 (s), 461 (w), 412 (s), 394 (w), 355 (w), 251 (s), 239 (w),
219 (w), 202 (w).

Preparation of [(2,2'-bpy)2Co(CH3CN)2](BF4)2 (6).

A sample of AgBF4 (2.35 g, 12.12 mmol) in 40 mL of acetonitrile was added

59

via a cannula to a 40 mL acetonitrile solution of (2,2'-bpy)2CoC12 (2.67 g,
6.05 mmol). The AgCl by-product was removed by passing the orange
solution through Celite. The volume of solution was reduced to ~5-10 mL,
and 40 mL of diethyl ether was added to induce precipitation of an orange
solid. The diethyl ether was decanted, and the orange solid was dried in
vacuo. Yield: (2.92 g, 77%) IR data (KBr and CsI plates with Nujol, cm"):
3480 (in), 3134 (w), 3096 (w), 2312 (s), 2280 (s), 1608 (s), 1601 (s), 1580
(m), 1570 (m), 1504 (w), 1493 (m), 1319 (m), 1284 (m), 1250 (m), 1180
(w), 1163 (m), 1059 (s, br), 895 (w), 765 (s), 734 (m), 653 (m), 626 (m), 581
(w), 572 (w), 559 (w), 520 (s), 497 (w), 479 (w), 465 (w), 446 (w), 421 (m),
391 (w), 375 (w), 360 (w, br), 280 (m), 244 (w), 208 (w).

Preparation of [(2,2'-bpy)2Ni(CH3CN)z](BF4)z (7).

A 20 mL acetonitrile solution of (2,2'-bpy)2NiC12 (0.592 g, 1.34 mmol)15
was treated with an acetonitrile solution of AgBF4 (0.522 g, 2.69 mmol) in
20 mL). The AgCl was collected on a Celite plug and the pale pink/purple
filtrate was reduced under vacuum. Once the solution volume had been
reduced to ~5-10 mL, 40 mL of diethyl ether were added to precipitate a
pale pink/purple solid. The diethyl ether was decanted through a cannula,
and the resulting pale pink/purple solid was dried in vacuo. Yield: (0.463 g,

55%) IR data (CsI plates with Nujol, cm"): 3495 (m), 1637 (m, br), 1603 (s),

60

1577 (s), 1568 (s), 1496 (m), 1444 (s), 1315 (m), 1286 (w), 1250 (m), 1224
(w), 1178 (w), 1060 (s, br), 895 (w), 769 (s), 736 (m), 655 (m), 636 (m), 554
(w), 521 (s), 445 (w), 418 (s), 394 (w), 355 (w), 282 (s), 252 (w).

(3) Preparation of [(phen)2N1(CH3CN)2](BF4)2 (8).

A sample of (phenbNiClonZO (0.573 g, 1.13 mmol)15 in 40 mL of
acetonitrile was treated with a solution of AgBF4 (0.411 g, 2.12 mmol) to
give a AgCl precipitate and a purplish colored solution. The solution was
allowed to stir overnight (~12 h) to ensure complete removal of the chloride
ligands. The AgCl was removed by filtration through Celite under a nitrogen
atmosphere. The resulting pale pink-purple solution was reduced in volume
to ~5-10 mL, and a 40 mL portion of diethyl ether was added to induce
precipitation of a pale pink/purple solid. The diethyl ether was removed by
cannula techniques and the pale pink/purple solid was dried in vacuo. Yield:
(0.584 g, 77%) IR (Nujol, cm“'): 2318 (s), 2289 (s), 1645 (m, br), 1628 (m),
1606 (m), 1587 (m), 1520 (s), 1496 (w), 1429 (s), 1344 (m), 1307 (m), 1286
(w), 1226 (m), 1212 (w), 1198 (w), 1151 (m), 1086 (s), 1060 (s), 1053 (s),
1034 (s), 871 (m), 846(8), 807 (w), 777 (m), 769 (w), 645 (m), 520 (w), 508
(w), 484 (w), 426 (w).

(4) Preparation of [(2,2'-bpy)2Ni(CH3CN)2](PF6)2 (9).

A quantity of TlPF6 (1.13 g, 3.24 mmol) was dissolved in 40 mL of

61

acetonitrile and treated with a 40 mL acetonitrile solution of (2,2'-bpy)2NiC12
(0.714 g, 1.62 mmol) which was added through a cannula.'5 The AgCl was
removed by filtration though Celite, the pale pink/purple filtrate was reduced
under vacuum to 5-10 mL, and 40 mL of diethyl ether were added to
precipitate a pale pink/purple solid. The diethyl ether was removed by
cannula techniques and the pale pink/purple solid was dried in vacuo. Yield:
(1.02 g, 85%) IR data (Nujol, cm"): 2314 (s), 2284 (s), 1608 (m), 1602 (s),
1579(8), 1571 (m), 1495 (m), 1446(8), 1412 (m), 1365 (m), 1315 (m), 1251
(m), 1220 (w), 1178 (m), 1166 (m), 1106 (w), 1046 (w), 1024 (m), 1016
(m), 966 (w), 937 (w), 841 (8, br), 760 (s), 736 (s), 653 (m), 634 (m), 607
(m), 557 (s), 483 (w), 468 (w), 444 (w), 416 (m).

(5) Preparation of (2,2'-bpy)2M(CF3SO3)2 (M = Mn" (10) and Co“ (11)).
Preparation of [(2,2'-bpy)2Mn(CF3803)z] (10).

A sample of (2,2'-bpy)2MnC1202H20 (0.681 g, 1.44 mmol) was dissolved in
40 mL of acetonitrile and treated with two equivalents of Ag(CF3SO3)
(0.975 g, 3.80 mmol) dissolved in 40 mL of acetonitrile. The reaction was
stirred for 12 h, after which time the AgCl was removed by filtration through
Celite. The solution was reduced in volume to ~5-10 mL, and 40 mL of
diethyl ether were added to precipitate the yellow product. Yellow crystals

were grown by slow diffusion of diethyl ether and hexanes into an

62

acetonitrile solution of the compound. Yield: (0.774 g, 78%) Anal. Calc. for
C22H16N4S206F6Mn: C 39.71; H 2.42; N 8.42. Found: C 39.87; H 2.64; N
7.60. IR (Nujol, cm'l): 1606 (s), 1599 (s), 1577 (m), 1493 (m), 1444 (s, br),
1311 (s), 1242 (s), 1234 (s), 1215 (s), 1180 (s), 1165 (s), 1024 (s), 769 (s),
738 (m), 653 (m), 636 (s), 581 (w), 572 (w, br), 516 (m), 416 (m), 358 (w,
br), 249 (m), 221 (w).

Preparation of [(2,2'-bpy)2Co(CF3SO3)2] (11).

A quantity of (2,2'—bpy)2CoClzo3HzO (0.841 g, 1.10 mmol) was dissolved in
40 mL of acetonitrile and combined with two equivalents of Ag(CF3SO3)
and (0.872 g, 3.39 mmol) in 40 mL of acetonitrile. The reaction was stirred
for 12 h, after which time the AgCl was removed by filtration through
Celite. The solution was reduced in volume to ~5-10 mL, and 40 mL of
diethyl ether were added to precipitate the product. The compound was
isolated as a dark orange solid. Orange crystals were obtained by slow
evaporation of an acetonitrile solution. Yield: (0.922 g, 78%) IR (CsI plates
with Nujol, cm'l): 1608(8), 1601 (s), 1577 (m), 1493 (m), 1444 (8, br), 1311
(s), 1242 (s), 1232 (s), 1213 (s), 1176 (m), 1157 (5, br), 1024 (s), 769 (s),
738 (m), 653 (m), 636 (s), 581 (w), 572 (w, br), 516 (m), 419 (m), 359 (w,
br), 280 (m), 244 (w, br), 208 (w).

(6) Preparation of [(phen)2Mn(CF3SO3);] (12).

63

A sample of (phen)2MnC1202H2016 (0.540 g, 1.04 mmol) was dissolved in
40 mL of acetonitrile and reacted with two equivalents of Ag(CF3SOg)
(0.603 g, 2.35 mmol) in 40 mL of acetonitrile. The reaction was stirred for
12 h, after which time the AgCl was removed by filtration through Celite.
The solution was reduced in volume to ~5-10 mL, and 40 mL of diethyl
ether were added to precipitate the yellow product. Yield: (0.379 g, 51%). IR
(Nujol, em"): 1625 (m), 1605 (w), 1592 (m), 1581 (m), 1522 (m), 1513 (m),
1496 (m), 1429 (s), 1347 (m), 1307 (s), 1259 (s), 1234 (s), 1215 (s), 1182
(s), 1167 (s), 1143 (s), 1105 (m), 1042 (s), 1022 (s), 997 (m), 966 (w), 868
(m), 848 (s), 815 (m), 804 (m), 785 (m), 761 (m), 731 (s), 636 (s), 584 (m),
572 (m), 516 (m), 501 (w), 422 (m).

(7) Preparation of [N i(2,2'-bpy)2(H20)2](CF3SO3)¢-2H20 (13).

A sample of (2,2‘-bpy)2NiC120HzO (0.873 g, 1.90 mmol)15 was dissolved in
40 mL of acetonitrile and reacted with two equivalents of Ag(CF3SO3)
(0.975 g, 3.80 mmol) in 40 mL of acetonitrile. The reaction was stirred for
12 h, the AgCl was removed by filtration through Celite, and the solution
was reduced in volume to ~10 mL. Treatment of the solution with 40 mL of
diethyl ether led to the precipitation of a purple solid. Purple crystals were
grown by slow evaporation of a water solution in air. Yield: (1.00 g, 75%).

Anal. Calc. for C22H24N4S2010F6Ni: C 35.65; H 3.26; N 7.55. Found: C

64

36.93; H 2.49; N 7.21. IR (CsI plates with Nujol, cm'l): 1610 (s), 1603 (s),
1579 (m), 1493 (m), 1448 (8, br), 1307 (s), 1244 (s), 1232 (s), 1217 (s), 1176
(s), 1161 (s), 1028 (s), 771 (s), 738 (m), 653 (m), 636 (s), 581 (w), 572 (w),
517 (m), 420 (m), 359 (w, br), 297 (m), 260 (m), 220 (w).

(8) Preparation of (phen)2Mn(NO3)2 (14).

A sample of (phen)2MnC1202H2016 (0.308 g, 0.590 mmol) was dissolved in
20 mL of acetonitrile and combined with two equivalents of AgNO3 (0.207
g, 1.22 mmol) in 20 mL of acetonitrile. The reaction was stirred for 12 h,
after which time the AgCl was removed by filtration through Celite. The
solution was reduced in volume to ~5-10 mL, and 40 mL of diethyl ether
were added to precipitate the product, which was collected by filtration and
dried. The compound was isolated as a yellow solid. Yield: (0.211 g, 67%)
IR data (Nujol, em"): 1641 (w), 1624 (m), 1591 (m), 1577 (m), 1518 (s),
1494 (m), 1428(8), 1412 (s), 1349(8), 1328(8), 1303 (s), 1298 (s), 1261 (s),
1223 (m), 1208 (w), 1100 (8, br), 1018 (s, br), 864 (m), 844 (s), 798 (8, br),
702 (w), 686 (w), 660 (w), 638 (m), 554 (w), 510 (w), 496 (w), 478 (w), 416
(w).

(9) Preparation of (phen)2Co(NO3)¢ (15).

A quantity of (phen)2CoC1202HzO (0.237 g, 0.451 mmol) was dissolved in

20 mL of acetonitrile and treated with two equivalents of AgNO; (0.153 g,

65

0.901 mmol) in 20 mL of acetonitrile. The reaction was stirred for 12 h, after
which time the AgCl was removed by filtration through Celite. The solution
was reduced in volume to ~5-10 mL, and 40 mL of diethyl ether were added
to precipitate the product. The compound was isolated by filtration as an
orange solid. Yield: (0.210 g, 86%) IR (Nujol, cm'l): 1625 (m), 1605 (w),
1582 (m), 1518 (s), 1494 (m), 1423 (s), 1292 (8, br), 1142 (s), 1101 (s), 1034
(m), 1024 (m), 993 (w), 972 (w), 959 (w), 869 (m), 847 (s), 826 (w), 776
(m), 750 (w), 643 (m), 554 (w), 508 (w), 479 (w), 443 (w), 424 (m).

(10) Preparation of (2,2'-hpy),M(CN)2 (M = Mn“ (16) and Co“ (17)).
Preparation of (2,2'-bpy)2Mn(CN)2 (16).

The literature preparation of (phen)2Mn(CN)203H20 was modified by

6 A solution of

replacing 1,10-phenanthroline with 2,2'—bipyridine.l
MnSO404HzO (0.525 g, 2.35 mmol) in 6 mL of CH3OH and 24 mL of H20
was added to a solution of 2,2'-bpy (0.971 g, 6.23 mmol) in a mixture of 20
mL of CH3OH and 80 mL of H20. This mixture was heated to 80°C under a
nitrogen atmosphere to prevent aerial oxidation, and maintained at this
temperature during the gradual addition of a KCN (0.606 g, 9.33 mmol)
solution (16 mL CH3OH/64 mL H20). As the product slowly cooled, air-

sensitive yellow needles were observed to form. Yield: (0.619 g, 56%) IR

(Nujol, cm“) on KBr plates: 2114 (m), 1595 (s), 1574 (m), 1491 (m), 1441

66

(s), 1315 (m), 1261 (m), 1097 (m, br), 1060 (m), 1014 (s), 802 (m, br), 769
(s), 736 (m), 646 (m), 625 (m), 489 (w, br).

Preparation of (2,2'-bpy)zCo(CN)2 (17).

A procedure similar to the one described above for (2,2-bpy)2Mn(CN)2 (16),
was followed for the preparation of the Co(II) derivative. A solution of
CoSO404H20 (0.549 g, 1.96 mmol) in 6 mL of CH3OH and 24 mL of H20
was added to a solution of 2,2'-bpy (0.610 g, 3.91 mmol) in a mixture of 20
mL of CH3OH and 80 mL of H20. This mixture was heated to 80°C under a
nitrogen atmosphere to prevent aerial oxidation, and maintained at this
temperature during the slow addition of a KCN (0.255 g, 3.92 mmol)
solution (16 mL CH3OH/64 mL H20). The product was slowly cooled to
yield yellow needles. Yield: (0.292 g, 35%) IR (KBr plates with Nujol, cm’
1): 2156 (w), 2123 (m), 1635 (m), 1599 (m), 1576 (m), 1315 (m), 1248 (m),
1157 (m), 1020 (m), 769(8), 736 (m), 652 (m), 630 (w), 412 (m).

(11) Preparation of [(4,4'-(CH3)2-2,2'-bpy)2CrClz]Cl (18).

Two equivalents of 4,4'-(CH3)2-2,2'-bpy (0.987 g, 5.37 mmol) in 25 mL of
acetonitrile were added dropwise into an acetonitrile solution of
(THF)3CrC13 (1.01 g, 2.69 mmol). An instantaneous color change fi'om
purple to green ensued with the formation of a green precipitate in a green

solution. The green precipitate was collected by filtration and washed with 2

67

x 20 mL of diethyl ether. The green filtrate was reduced in volume to ~10
mL, and 40 mL of diethyl ether were added to precipitate the green product.
The solution was removed by cannula techniques and the green solid was
dried in vacuo. Yield: (1.12 g, 80%) IR (Nujol, em"): 1615 (m), 1591 (m),
1551 (m), 1486 (w), 1408 (w), 1364 (m), 1340 (w), 1321 (w), 1303 (m),
1279 (m), 1260 (w), 1239 (m), 1219 (m), 1102 (w), 1026 (m), 991 (m), 970
(w), 922 (m), 911 (m), 823 (s), 738 (m), 669 (m), 607 (w), 589 (w), 563 (m),
516 (s), 488 (w), 466 (w), 421 (m), 418 (m).

(12) Preparation of [(4,4'-(CH3)2-2,2'-bpy)2FeClz]Cl (19).

Two equivalents of 4,4'-(CH3)2-2,2'-bpy (1.58 g, 8.58 mmol) in 25 mL of
acetonitrile were added dropwise to an acetonitrile solution of F eCl; (0.695
g, 4.29 mmol) which effected an instantaneous color change from red/orange
to yellow with the deposition of a yellow precipitate from a yellow solution.
The yellow precipitate was removed by filtration and washed with 2 x 20
mL of diethyl ether. The yellow filtrate was reduced in volume to ~5-10 mL.
Diethyl ether (40 mL) was added to precipitate the yellow product and the
solution was decanted. The yellow product was dried in vacuo. Yield: (1.60
g, 70%) IR (Nujol, cm"): 1612 (s), 1554 (m), 1407 (w), 1304 (m), 1281 (w),
1242 (m), 1219 (w), 1203 (w), 1166 (w), 1153 (w), 1121 (w), 1078 (w),

1035 (w), 1018 (s), 968 (w), 922 (m), 897 (w), 845 (m), 831 (m), 770 (w),

68

740 (m), 669 (w), 553 (m), 518 (m), 482 (w), 422 (m), 418 (In).

(13) [(434'-(CH3)2-2,2'-bPY)2Fe(CN)21(PFt) (20)-

Two equivalents of AgCN (0.093 g, 0.694 mmol) in 10 mL of acetonitrile/10
mL methanol were added to a 10 mL acetonitrile/ 10 mL methanol solution
of [(4,4'-(CH3)2-2,2'-bpy)2FeC12]Cl (0.184 g, 0.347 mmol). This was allowed
to react for 30 minutes, after which time one equivalent of TlPF6 (0.122 g,
0.349 mmol) in 10 mL acetonitrile was added. After two days of stirring, the
solution was filtered, and the red filtrate was reduced in volume; addition of
40 mL of diethyl ether led to the precipitation of a red solid. The diethyl
ether was removed using cannula techniques and the red product was dried
in vacuo. Yield: (0.065 g, 30%) IR (Nujol, cm"): 2064 (m), 1618 (s), 1556
(m), 1412 (w), 1352 (w), 1305 (m), 1286 (w), 1264 (w), 1242 (m), 1225 (w),
1202 (w), 1166 (m), 1155 (m), 1078 (w), 1038 (w), 1024 (m), 971 (w), 924
(m), 908 (w), 843 (8, br), 773 (w), 736 (w), 670 (w), 557 (s), 531 (m), 518
(m), 494 (w), 486 (w), 467 (w), 424 (m).

C. Reactivity Studies

(1) Reaction of (2,2'-bpy)2Co(CN)2 with [(2,2'-bpy)2Co(CH3CN)2](BF4)z.
One equivalent of [(2,2'-bpy)2Co(CH3CN)2](BF4)2 (0.123 g, 0.298 mmol)
dissolved in 20 mL of acetonitrile was combined with one equivalent of

(2,2'-bpy)2Co(CN)2 (0.187 g, 0.298 mmol) in 20 mL of acetonitrile. A tan/

69

light-brown precipitate formed in a colorless solution, and was decanted
from the solid. The precipitate was washed with 40 mL of diethyl ether and
dried in vacuo. IR (Nujol, cm“): 2248 (w), 2147 (m), 1666 (m), 1608 (s),
1568 (m), 1504 (m), 1321 (m), 1284 (m), 1261 (s), 1180 (m), 1057 (s, br),
895 (w), 800 (s), 771 (s), 673 (w), 651 (w), 559 (w), 520 (m), 497 (w), 480
(w), 460 (w), 422 (m).

(2) Reaction of (2,2'-bpy)2Co(CN)2 with [(phen)2Ni(CH3CN)2](BF4)z.

One equivalent of [(phen)2Ni(CH3CN)2](BF4)2 (0.167 g, 0.248 mmol) in 5
mL of acetonitrile was reacted with one equivalent of (2,2'—bpy)2Co(CN)2
(0.105 g, 0.248 mmol) in 5 mL of acetonitrile. The solution turned green
with the formation of a blue precipitate. The solution was decanted, and the
blue precipitate was washed with 40 mL of diethyl ether and dried in vacuo.
IR data (Nujol, cm"): 2166 (m), 1672 (w), 1628 (w), 1606 (m), 1518 (m),
1315 (w), 1147 (w), 1062 (s, hr), 870 (w), 848 (m), 769 (m), 652 (w).

(3) Reaction of (2,2'-bpy)2Co(CN)2 with [(phenth(CF3SO3)2].

One equivalent of (phen)2Mn(CF3SO3)2 (0.133 g, 0.187 mmol) in 20 mL of
acetonitrile was reacted with one equivalent of (2,2'-bpy)2Co(CN)2 (0.071 g,
0.168 mmol) in 20 mL of acetonitrile. The solution slowly turned gold with
the deposition of a yellow/tan precipitate from a colorless solution. The

solution was removed via a cannula, and the tan solid was washed with 20

70

mL of diethyl ether. The solvent was removed by cannula techniques and the
solid was dried in vacuo. IR (Nujol, cm‘l): 2158 (s), 1604 (m), 1520 (m),
1427 (m), 1344 (w), 1304 (m), 1261 (s), 1238 (s), 1223 (s), 1157 (m), 1103
(m), 1030 (s), 848 (m), 769 (m), 729 (m), 636 (s), 451 (m).
(4) Reaction of (4,4'-‘Bu-2,2'-bpy)2Co(CN)2 with [(2,2'-bpy)2N i
(CH3CN)2](PF6)2-
One equivalent of [(2,2'-bpy)2Ni(CH3CN)2](PF6)2 (0.098 g, 0.131 mmol) in
15 mL acetonitrile was added to a 15 mL acetonitrile solution of (4,4'-‘Bu-
. 2,2'-bpy)2Co(CN)2 (0.102 g, 0.157 mmol). The reaction was performed
aerobically in wet acetonitrile, and allowed to stir for 12 h during which time
the solvent evaporated. The yellow/orange solid was redissolved in
acetonitrile, and the solution was slowly evaporated to yield yellow/orange
crystals. IR (Nujol, cm’l): 3400 (5, br), 2177 (m), 1608 (s), 1577 (m), 1550
(m), 1446(8), 1412 (s), 1315 (s), 1251 (s), 1186 (m), 1161 (m), 1024 (s),
841 (5, br), 736 (s), 653 (s), 634 (s), 607 (s), 557 (s), 416 (m).
D. SINGLE CRYSTAL X-RAY STRUCTURAL STUDIES
Crystallographic data for compounds 7, 10 and 16 were collected on a
SMART 1K and for 13 and 21 on a SMART 2000 CCD diffractometer
equipped with monchromated Mo K01 (7..Cl = 0.71069 A) radiation. The

source is a Mo sealed tube with a 3 KW generator. The frames were

71

integrated in the Bruker SAINT software package17 and the data were
corrected for absorption using the SADABS program.18 The SIR97l9 and
SI-IELX-9720 crystallographic software packages were used to solve and
refine the crystal structures. Crystal parameters and basic information

pertaining to data collection and structure refinement are summarized in

Tables 2.1-2.3.

(1) [(2,2'-bPY)2Ni(CH3CN)2l(BE): (7)-

Single crystals of 7 were grown by reducing the volume of an acetonitrile
solution of the compound under vacuum. A purple crystal of dimensions
0.25 x 0.20 x 0.15 mm3 was mounted on the tip of a glass fiber with Dow
Corning silicone grease and placed in a cold N2 stream. Least squares
refinement using well-centered reflections in the range 2.70 < 20 < 46.60
gave a cell corresponding to a triclinic crystal system. A total of 9289 data
(3908 unique) with F (000) = 624 were collected at 173(2) K using the 61-20
scan technique to a maximum 20 value of 46.60. The space group was
determined as P-l. The final full-matrix, least-squares refinement was based
on data with F02 > 40(F02) and parameters to give R1 = 0.0414 (sz =
0.1077) and Rim = 0.0328. The goodness-of-fit index was 0.710, and the
highest peak in the final difference map was 0.512 e'/A3. All non-hydrogen

atoms were refined anisotropically. The hydrogen atoms were placed in

72

Table 2.1. Crystallographic information for [(2,2'- bpy)2Ni(CH3CN)2](BF4)2
(7) and [(2,2'-bpy)2Ni(0H2)2](033CF3)2 (13)'2H20-

 

7 l3 02HZO

Formula C24H16FgNiN6B2 C22H24F6N4NiOwSz
Formula weight 620.76 741.28
Temperature (K) 173(2) 110(2)
Space group P-1 P-1
a (A) 9.990(5) 11.325(5)
b (A) 10.255(5) 11.968(5)
c (A) 15.290(5) 12.791(5)
01 (°) 90.975(5) 81.134(5)
[3 (°) 96.600(5) 71.290(5)
7 (°) 119.051(5) 64.114(5)
Volume (A3) 1355.5(10) 1477.1(11)
Z 2 2
Dc,lc (Mg m'3) 1.521 1.667
Absorption coefficient(mm'1) 0.797 0.896
Crystal size (mm) 0.25x0.20x0.15 0.30x0.372x0.063
Reflections collected 9289 6716
Independent reflections 3908 5448
Rim 0.0328 0.0182
Final R indices R1 = 0.0414 R1 = 0.0447

sz = 0.1077 sz = 0.1058

 

R1 = 2mm - IF, II] / 2111.1. sz = {2mm} — 13,2)2 / Z[w(F02)2]}”2. GOF =
{2[W(F02 - Fc2)2] / (n — p)}”2 where n = total number of reflections and p =

total number of parameters.

73

Table 2.2. Summary of crystallographic data for Mn(O3SCF3)2(2,2'-bpy)2

(10) and for Mn(CN)2(2,2'-bpy)2 (l6) 03HZO.

 

 

10 16 03HZO

Formula C22H16F6MnN4O6SZ C22H22MnN603
Formula weight 665.45 473.40
Temperature (K) 173(2) 173(2)
Space group C2/c P21/n
a (A) 10.0240) 8.544(1)
b (A) 14.2370) 19.989(1)
c (A) 18.9220) 13.4480)
on (°) 90 90
[3 (°) 101.32(1) 90.065(1)
7 (°) 90 90
Volume (A3) 647.9(4) 2296.87(11)
Z 4 4
Dcalc (Mg m'3) 1.669 1.369
Absorption coefficient(mm'l) 0.745 0.610
Crystal size (mm) 0.52 x 0.47 x 0.18 0.25 110.25 x 0.10
Reflections collected 8163 13655
Independent reflections 31 18 5333
Rim 0.0267 0.0362
Final R indices R1 = 0.0379 R1 = 0.0448

wR2 = 0.1035 wR2 = 0.0796

 

R1 = 21111201 - IF, ll] / 2w. wR2 = {1:090:02 — F32 / 2[w(F02)2]}”2. GOF =
{2‘.[w(F.,2 -— Fc2)2] / (n - 12))"2 where n = total number of reflections and p =

total number of parameters.

74

Table 2.3. Crystallographic Information for [Co(CN)2(4,4'-‘Bu-2,2'-

 

 

bPY)2](PF6) (21) ‘H20
21 OHZO
Formula C33H50C0N60P1F6
Formula weight 805.73
Temperature (K) 100(2)
Space group P -1
a (A) 10.888(5)
b (A) 16.059(5)
c (A) 24.917(5)
01 (°) 105.612(5)
B (°) 90.225(5)
Y (°) 97.899(5)
Volume (A3) 4152(2)
Z 4
Dcalc (Mg m'3) 1.295
Absorption coefficient(mm'1) 0.515
Crystal size (mm) 0.16 x 0.034 x 0.020
Reflections collected 21089
Independent reflections 16214
Rim 0.2171
Final R indices R1 = 0.0815
wR2 = 0.1760

 

R, = 201m - IFc ll] / 21m. wR2 = {20012} — 12,62 / Z[w(F02)2]}”2. GOF =
{2[W(F62 - Fe2)2] / (n — p)}“2 where n = total number of reflections and p =

total number of parameters.

calculated positions and treated as riding atoms. A thermal ellipsoid plot is
presented in Figure 2.3.

(2) (2,2'-bPY)2Mn(CF3$03)2 (10)-

Single crystals of 10 were grown by slow diffusion of diethyl ether/hexanes
into an acetonitrile solution of the compound at room temperature. A pale-
yellow crystal of dimensions 0.52 x 0.47 x 0.18 mm3 was mounted on the tip
of a glass fiber with Dow Corning silicone grease and placed in a cold N2
stream. Least squares refinement using well-centered reflections in the range
4.40 < 20 < 56.40 gave a cell corresponding to a monoclinic crystal system.
A total of 8163 data (3118 unique) with F(000) = 1340 were collected at
173(2) K using the (1)-20 scan technique to a maximum 20 value of 56.40.
Systematic absences from the data led to the choice of C2/c as the space
group. The final full-matrix, least-squares refinement was based on data with
1:,2 > 40(F02) and parameters to give R1 = 0.0379 (sz = 0.1035) and Rint =
0.0267. The goodness-of-fit index was 1.024, and the highest peak in the
final difference map was 0.684 e’/A3. All non-hydrogens atoms were refined
anisotropically. Hydrogen atoms were placed in calculated positions as
riding atoms. A thermal ellipsoid plot is presented in Figure 2.4.

(3) [(2,2'-bPY)2Ni(0H2)21(CF3503)2 (13)-

Single crystals of 13 were grown by slow evaporation of an acetonitrile

76

solution of the compound at room temperature. A purple crystal of
dimensions 0.30 x 0.37 x 0.063 mm3 was mounted on the tip of a glass fiber
with Dow Corning silicone grease and placed in a cold N2 stream. Least
squares refinement using well-centered reflections in the range 3.36 < 20 <
56.48 gave a cell corresponding to a triclinic crystal system. A total of 11001
data (6716 unique) with F(000) = 756 were collected at 110(2) K using the
00-20 scan technique to a maximum 20 value of 56.48. The space group was
determined to be P-l. The final full-matrix, least-squares refinement was
based on data with F02 > 40(F02) and parameters to give R1 = 0.0449 (wR2 =
0.1058) and Rim = 0.0182. The goodness-of-fit was 1.069, and the highest
peak in the final difference map was 1.490 e’/A3. All non-hydrogen atoms
were refined anisotropically. Hydrogen atoms were placed in calculated
positions as riding atoms. A thermal ellipsoid plot is depicted in Figure 2.5.
(4) (2,2'-bPY)2Mn(CN)2 (16) ~3H20-

Single crystals of 16 were grown by slow cooling of the methanol/water
solution from 80 °C to room temperature. A pale-yellow crystal of
dimensions 0.25 x 0.25 x 0.10 mm3 was mounted on the tip of a glass fiber
with Dow Corning silicone grease and placed in a cold N2 stream. Least
squares refinement using well-centered reflections in the range 3.66 < 20 <

56.48 gave a cell corresponding to a monoclinic crystal system. A total of

77

13655 data (5333 unique) with F(000) = 980 were collected at 173(2) K
using the 01-20 scan technique to a maximum 20 value of 56.48. Systematic
absences from the data led to the choice of P21/n as the space group. The
final full-matrix, least-squares refinement was based on data with F02 >
46013) to give R1 = 0.0448 (sz = 0.0796) and Rint = 0.0362. The
goodness-of-fit was 1.052, and the highest peak in the final difference map
was 0.277 e'/A3. A thermal ellipsoid plot is shown in Figure 2.6.

(5) [(4’4"tBu'292"bPY)2C0(CN)2](PF6) (21)

Single crystals of 21 were grown by slow evaporation of an acetonitrile
solution at room temperature. A pale orange-yellow crystal of dimensions
0.16 x 0.034 x 0.020 mm3 was mounted on the tip of a glass fiber with Dow
Corning silicone grease and placed in a cold N2 stream. Least squares
refinement using well-centered reflections in the range 2.66 < 20 < 56.56
gave a cell corresponding to a monoclinic crystal system. A total of 21089

(16214 unique) data were collected at 100(2) K using the 60-20 scan
technique to a maximum 20 value of 56.56. The final full-matrix, least-

squares refinement was based on data with F,2 > 40(F02) and parameters to

give R. = 0.0815 (wR2 = 0.1760) and Rim = 0.2171. The transmission factors
are in the range of 0.577 to 1.00. The goodness-of-fit index was 0.732, and

the highest peak in the final difference map was 0.728 e'/A3. A thermal

78

      

.l/I; Ni“)
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Figure 2.3. Thermal ellipsoid representation of the cation,
[(2,2'-bpy)2Ni(CH3CN)2]2+ , in (7) at the 50 % probability level.
The hydrogen atoms were omitted for the sake of clarity.
(Image is presented in color)

79

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Figure 2.4. Thermal ellipsoid representation of (2,2'-bpy)2Mn(CF3SO3)2,
(10), at the 50 % probability level. Hydrogen atoms were
omitted for the sake of clarity.

80

 

 

 

Figure 2.5. Thermal ellipsoid representation of the cation,
[Ni(2,2'-bpy)2(OH2)2]2+, in (13) at the 50% probability level.
Hydrogen atoms are omitted for the sake of clarity.

81

 

Figure 2.6. Thermal ellipsoid representation of (2,2'-bpy)2Mn(CN)2 (16)
at the 50 % probability level. The hydrogen atoms were
omitted for the sake of clarity.

82

 

Figure 2.7. Thermal ellipsoid representation of the cation, [(4,4'-‘Bu-2,2'-
bpy)2Co(CN)2]+, in (21) at the 50 % probability level. The

hydrogen atoms were omitted for the sake of clarity.
(Image is presented in color)

83

ellipsoid plot is presented in Figure 2.7.

3. RESULTS AND DISCUSSION

A. Syntheses of [(N-N)2M(S)2]2+ salts (N-N = 2,2'-bipyridine, 2,2'-
bipyrimidine or 1,10-phenanthroline and S = H20, CH3CN, CH3OH or
N05).

The preparation of compounds of the type (2,2'-bypm)2MC12 in 1986 by
Ruminiski and co-workers14 paved the way for using such complexes as
precursors for building larger clusters. The addition of two equivalents of a
halide abstraction agent such as AgBF4, Ag(CF3SO3), AgNO3 or TlPF6
allows for two sites on the octahedral metal ion to be made available.
(Figure 2.1.) These labile sites are occupied by either solvent molecules or
weakly coordinating anions, which are readily displaced by stronger donors.
We reasoned that if this chemistry works with the 2,2'-bpym ligand, then
analogous chemistry should also be possible with 1,10-phenanthroline or
2,2'-bipyridine just as well. The coordination chemistry of these diimine
ligands has been studied extensively, and it is known that steric interactions
between the a—hydrogen atoms of opposite ligands for two 1,10-
phenanthroline or 2,2'—bipyridine ligands disfavors a trans planar
arrangement. Two 2,2'-bpy or phen ligands are, therefore, forced to adopt a

cis configuration on an octahedral metal ion.”

84

(1) [(2.2'-bpym)zM(0H2)21(BF.)z (M = Mn“ (1), Fe“ (2). Co" (3) and

Ni“ (4).

The [(2,2'-bpym)2M(OH2)2](BF4)2 series of compounds were the first group
of this type to be synthesized. Unfortunately, the products were obtained in
poor yields and have not been able to be crystallized as suitably large single
crystals for X-ray diffraction studies. These complexes are more difficult to
synthesize due to the relatively high lability of the 2,2'-bpym groups in the
presence of water molecules, which participate in hydrogen bonding at the
uncoordinated N-N units. This increases the lability of the ligand and hence
the rates of ligand redistribution, the ultimate result of which is the
formation of the [M(2,2'-bpym)3]2+ species. This problem is particularly
prevalent in reactions with FeC 12, which is difficult to dry and prone to
oxidation.

The compounds were characterized by infrared spectroscopy, which is a
good diagnostic tool for investigating the mode of the 2,2'—bpym ligand. The
2,2'-bpym molecule exhibits ring stretching v(C=C), v(C=N) modes at 1570,
1545 and 1400 cm".22 If the 1570 and 1545 cm'1 stretches appear as doublets

then the 2,2'-bpym is bound in the mono-chelating mode. If the two stretches
are quasi-symmetric, the 2,2'-bpym ligand is acting as a bis-chelator. In the

case of uncoordinated 2,2'—bpym, an intense stretch (combination of v(C=C),

85

v(C=N)) appears at 1420 cm’l. Table 2.4 summarizes the IR data for the
series [(2,2'-bpym)2M(OH2)2](BF4)2. Electrospray mass spectrometry was
conducted on [(2,2'-bpym)2Ni(OH2)2](BF4)2 in a water/acetonitrile mixture.
The parent ion peak in the spectrum appears at 187 m/z which corresponds
to the [M(2,2'-bpym)2]2+ fragment. The bound water molecules are
apparently easily lost under these conditions.

(2) [(N-N)2M(CH3CN)2](BF4)2 (M = Mn" (5), Co" (6) and Ni" (7 and 8)
with N-N = 2,2'-bpy or phen).

These compounds were synthesized from their anhydrous chloride
counterparts, viz., (N-N)2MC12. The IR data reveal two acetonitrile stretches,
which is consistent with the cis arrangement of CH3CN ligands on a
molecule with a C2v point group. The 2,2'-bpy or 1,10-phen stretches as well
as the acetonitrile stretches are summarized in Table 2.5. In the presence of
water, the CH3CN ligands are displaced in favor of H20. The 2,2'—bpy
stretches v(C=C), v(C=N) are typically in the range 1400-1600 cm'1 and a
ring torsion (1) occurs in the range 410-420 cm".23 The torsional ring motion
appears at about 20 cm'1 higher than that of the free ligand.23 There is an out-
of-plane hydrogen bend 8(C-H) at ~ 725 cm".

(3) [(2’2"bPY)2Ni(CH3CN)2](PF6)2 (9)-

This complex was synthesized from (2,2'-bpy)2NiC12 by removal of the

86

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chloride ligands with TlPF6 in dry acetonitrile. Although the chloride
complex does not appear to be soluble in acetonitrile, the green suspension is
gradually replaced by a pink/purple solution upon addition of TlPFG, with
the deposition of white T1Cl. IR data of the product reveals two acetonitrile
stretches (2314 (s) and 2284 (s) cm") as expected for the cis arrangement of
a C2,, molecule. The 2,2'—bpy stretches v(C=C), v(C=N) appear at 1608 (m),
1602 (s), 1579 (s), 1571 (m) and ring torsion (T) at 416 (m) cm". The
torsional ring motion appears about 20 cm'1 higher than that of the free
ligand.23 The v(P-F) stretch appears as a strong and broad peak at 841 cm".
(4) (N-N)2M(CF3O3S)2 (M = Mn" and Co"; N-N = 2,2'-bpy or phen).

The triflate complexes were synthesized from (N-N)2MC12by removing the
chlorides with Ag(CF3SO3). The coordinated phen and 2,2'-bpy ligands
exhibit stretches v(C=C), v(C=N) in the 1400-1600 cm’I region. There is also
a 2,2'-bpy ring torsion (1:) appearing at 420 cm". The torsional ring motion
appears about 20 cm’1 higher than that of the free ligand.23 Unambiguous
assignments of vibrational modes for [CF3SO3]' is not possible due to the
mixing of CF3 and SO; vibrational modes and accidental coincidences of
these modes arising particularly in the stretching region. The triflate anion

l

exhibits a characteristic symmetric stretch at v,(S-O) ~1024 cm' and an

asymmetric stretch va,(S-O) at ~1287 cm".24 Potential energy calculations

89

indicate a high contribution of v(C-S) to a band in the IR at 320 cm'l. The
band at 770 cm‘1 is due primarily to 8(C-F). The infiared data for these
complexes are summarized in Table 2.6.

(5) [(2,2'-bpy)2Ni(OH2)21((3173803). (13).

The reaction was performed in acetonitrile, but slow evaporation of the
acetonitrile solution in moist laboratory air produced purple crystals of the
water adduct. The purple crystals were verified by single crystal X-ray
diffraction to be [(2,2'-bpy)2Ni(OH2)2](CF3303)2. This complex exhibits
2,2'-bpy stretches v(C=C), v(C=N) at 1610, 1603 and 1579 cm'1 along with
2,2'-bpy ring torsion (I) at 420 cm'l and a v,(S-O) stretch at 1028 cm". The
torsional ring motion appears about 20 cm”1 higher than that of the free
ligand.”

(6) (phen)2M(NO3)2 (M = Mn" (14) and Co" (15)).

These complexes were synthesized from the (phen)2MC12 species by
removal of chlorides with silver nitrate. The 1,10-phen ligand stretches
v(C=C), v(C=N) for each complex are in the range of 1400-1600 cm". The
broad nitrate stretches span the region of the spectrum around 1200 cm".

(7) (2,2'-bpy)2M(CN)2 (M = Mn" (16) and Co" (17).

The cyanide complexes were prepared from a deoxygenated water-methanol

solution according to a literature preparation of (phen)2Mn(CN)2. Afier slow

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addition of the cyanide solution at 80 °C, the reaction is slowly cooled by
keeping the flask immersed in the silicone oil bath with a nitrogen purge. In
this manner, yellow crystals of (2,2'-bpy)2Mn(CN)2.3H20 admixed with
yellow precipitate can be obtained. Upon exposure of the product to air, an
immediate color change to brown ensues, signifying that the product is
decomposing. The corresponding Co reaction yields a tan/brownish
precipitate. The reaction with Ni(II) led to ligand redistribution as evidenced
by the isolation of pink crystals of the salt [N i(2,2'—bpy)3][N i(CN)4].2,2'-bpy
which was characterized by X-ray crystallography. The iron (11) reaction
produced red needle crystals fi'om an intensely colored red solution, but they
diffracted too poorly for a complete X-ray study to be performed. In
addition, a small quantity of a blue precipitate was observed which is
assumed to be Prussian blue due to loss of 2,2'-bpy fi'om all the Fe centers
and oxidation of some of the FeII to Fem.

A. Syntheses of Trivalent Precursors

The divalent metal precursors with cyanide such as complexes 16 and 17 of
the type (2,2'-bpy)2M(CN)2 are neutral species which makes them fairly
insoluble. One way to circumvent the neutrality is to prepare cis-dicyanide
complexes of trivalent metals, which renders them monocations, of the type,

[(2,2'-bpy)2M(CN)2]+. Possible candidates for this chemistry are d5 Fe(III)

92

and d3 Cr(III) complexes, which possess one and three unpaired electrons
respectively. In addition to the cationic charge, another option for improving
the solubility of the neutral compounds is to synthesize complexes with
substituted 2,2'-bpy or 1,10-phen ligands.

(1) [(4,4'-(CH3)2-2,2'-bpy)2MCl2]Cl (M = CH" (18) and Fe‘“ (19)).

The addition of two equivalents of 4,4'-(CH3)2-2,2'-bpy to (THF)3CrCl3 leads
to a green solution and a green precipitate which were judged to be the same
compound by infiared spectroscopy. Infrared data indicate the presence of
characteristic 4,4'-(CH3)2-2,2'-bpy stretches v(C=C), v(C=N) at 1615, 1591
and 1551 cm". The 4,4'-(CH3)2-2,2'-bpy ring torsion (1) appears at 420 cm".
In the case of the reaction of 4,4'-(CH3)2-2,2'—bpy with FeCl3, a yellow
solution and a yellow precipitate were obtained. Infrared spectral data
indicated that the yellow solution and precipitate are the same complex. IR
data reveals the presence of 4,4'-(CH3)2-2,2'-bpy activity in the form of
v(C=C), v(C=N) stretches that appear at 1612 and 1554 cm'1 and a ring
torsion (1:) mode at 420 cm".

(2) [(4,4'-(CH3)2-2,2'-bPY)2F C(CN)21(PF6) (20)-

This reaction was designed to replace Cl' with CN', thus AgCN was used as
the Cl' abstraction reagent as well as the CN‘ delivery agent. Since AgCN is

not very soluble in neat acetonitrile, a mixture of acetonitrile and methanol

93

was used. The reaction proceeded very slowly by visual inspection, and after
~30 minutes, one equivalent of thallium hexafluorophosphate was added.
Before the addition of the thallium complex the solution had turned light red.
Once the thallium was added, however, the solution became much more
deep red in color. The isolated red product was obtained in poor yield at
30%. The infiared data indicate that both cyanide (2064 cm'l) and 4,4'-
(CH3)2-2,2'-bpy, with v(C=C), v(C=N) stretches at 1618 and 1556 cm", are
present. The 4,4'-(CH3)2-2,2'-bpy ring torsion (I) mode appears at 424 cm".
There is also a strong, broad feature at 843 cm'1 due to v(P-F) of the [PF5]'
anion. Although this reaction appears to be working, the yield is poor and is
obviously not a preferred route to the desired dicyanide precursor.
C. Reactivity Studies
The formation of molecular squares of the type [(2,2'-bpy)gM2M2'(CN)4]n+
requires that one equivalent of a solvated precursor be combined with one
equivalent of a cyanide precursor. This type of reaction is depicted in Figure
2.2.
(1) Reaction between (2,2'-bpy)2Co(CN)2and
[(2,2'-bPY)2C0(CH3CN)2](BF4)2-
The cobalt reagents were combined in acetonitrile, but the reaction was slow

due to the insolubility of the neutral species. Over the course of one day, a

94

brown precipitate was isolated and found to exhibit a single cyanide stretch
at 2147 cm". This observation is taken as an indication that either a
molecular square has formed or that a polymer with only one type of cyanide
ligand is produced. Unfortunately, the brown precipitate is insoluble in most
common solvents, so no further characterization was possible.

(2)Reaction between (2,2'-bpy)2Co(CN)2 and [(phen)2Ni(CH3CN)z](BF4)2
One equivalent of each of these complexes was combined in a small volume
of acetonitrile. The color of the solution turned green, and a blue precipitate
formed within 15 min. The blue precipitate, which is insoluble in most
common solvents, exhibits a single cyanide stretch at 2166 cm", which, as
stated earlier, could be either a molecular square or a symmetrical polymer.
The blue precipitate was sent to the University of California at Berkeley for
electrospray mass spectrometry, but the results were inconclusive.

(3) Reaction between (2,2'-bpy)zCo(CN)2 and (phenth(CF3SO3)2.

A reaction of (2,2'-bpy)2Co(CN)2 and (phen)2 Mn(CF3SO3)2in a 1:1 ratio was
performed in acetonitrile. The solution turned gold, and within hours a
yellow-tan precipitate was present. The infrared data revealed a single,
strong, and very sharp, cyanide stretch at 2158 cm]. The triflate anion was
also evident from the v,(S-O) mode located at 1030 cm'l. The golden colored

solution was layered with hexanes and diethyl ether but it did not yield

95

crystals. The yellow-tan precipitate was also sent to the University of

California at Berkeley for electrospray mass spectrometry, but the results

were inconclusive.

(4) Reaction between (4,4'-'Bu-2,2'-bpy)2Co(CN)z and
[(2,2'-bPY)2Ni(CH3CN)2](PFsh-

The reaction was carried out in a 1:1 ratio of the parent compounds in

acetonitrile in air. No spontaneous formation of precipitate was observed,

but after slow evaporation of the acetonitrile solution, pale orange/yellow

crystals were obtained. The crystals indicated that the cobalt complex had

been oxidized from CeII to Com to yield [(4,4'-‘Bu-2,2'-bpy)2Co(CN)2](PF6)

(21). Obviously, since (4,4'-‘Bu-2,2'-bpy)2Co(CN)2 was prepared in air, and

with a methanol/water solution, this is sufficient to cause oxidation of the

metal center.

D. Molecular Structures.

(1) [(2,2'-bPY)2Ni(CH3CN)21(BF4)2 (7)-

The [(2,2'-bpy)2Ni(CH3CN)2]2+ cation possesses two 2,2'-bpy ligands acting

as typical bidentate ligands bound to Ni(l) through the nitrogen atoms. Two

acetonitrile molecules complete the octahedral environment around Ni(l).

The Ni(l)—N(2,2'-bpy) bond lengths are in the range of 2.075(3)-2.082(3)A,

and the Ni(l)-N(CH3CN) bond lengths are 2.091(4) and 2.094(4)A. The Ni-

96

N(CH3CN) distances are longer than the corresponding distances to the 2,2'-
bipyridine, indicating that they are, as expected, poorer ligands than the 2,2'-
bpy N atoms. The angles subtended by the five—membered rings created by
the bidentate 2,2'—bipyridine ligands are 78.99(12)° and 79.10(12)°. The
angle between the coordinated acetonitriles is 84.15(14)°. The C-N bonds
lengths in the acetonitrile ligands are 1.142(5)A and 1.141(5)A. Selected
bond distances and angles are given in Table 2.7.

(2) (2,2'-bPY)2Mn(CF3803)2 (10)-

The compound possesses two 2,2'-bpy ligands and two triflate anions bound
to the Mn atom through their respective oxygen atoms. The Mn(1)-N(2,2'-
bpy) bond lengths are 2.2355(16) and 2.2330(15)A while the Mn-
O(CF3SO3) bond distance is 2.1957(14)A. The bite angle of the 2,2'-bpy
chelate is 73.52(6)°. The angle between the two coordinated water molecules
is 86.61(8)°. Selected bond distances and angles are given in Table 2.8.

(3) [(ZJ'-bPYhNi(0szl(CF3803)2 (13)-

The structure consists of a Ni atom in an environment with four nitrogen
atoms from the two 2,2'-bipyridine ligands and two oxygen atoms from the
water molecules. The Ni( 1)—N(2,2'-bpy) bond distances are in the range of
2.064(2)A and 2.086(2)A and the Ni(1)eO distances are 2.059(2)A and

2.061(2)A. The angle between the two water molecules is 84.55(9)°. The

97

bite angles for the 2,2'-bpy chelates are 78.89(9)° and 79.29(9)°. There is a
slight distortion in 13 with the Ni(l)-N(10) bond being longer at 2.086(2)A
and the Ni(l)-N(9) being shorter at 2.064(2)A. By comparison, the structure
of the related compound, [N i(C(,HzO4)(dmbpy)2]°HzO,25 with one o-
benzoquinone ligand exhibits Ni-N(dmbpy) bond lengths in the range of
2.035(7)—2.072(8) A, which are slightly shorter than those for 13. The bite
angle is 79.1(3)°. The Ni-O bond lengths are in the range of 2.044(7)—
2.055(7) A, which are slightly shorter than for complex 13 indicating that
the o-benzoquinone is a better donor than a water molecule. The angle
between the two oxygen atoms is 79.4(3)°, which is less than the angle
between the water molecules of complex 13; this is likely due to the rigidity
of the chelate ligand. Selected bond distances and angles for compound 13
are provided in Table 2.9.

Another example similar to complex 13 is a dimeric species,26 [N i2(HzO)3(u-
2,2'-bpym)]4+, in which the nickel atoms are bridged by the bis-chelate, 2,2'-
bipyrimidine. The Ni-N(2,2'-bpym) bond distances are 2.092(3) and
2.097(3) A which are much longer than complex 13. The longer distance is
attributed to the fact the 2,2'-bpym ligand is acting as a bis-chelate and the
monochelate 2,2'-bpy is a stonger ligand than is 2,2'-bpym. The bite angle

for the 2,2'-bpym ligand is 79.2(l)°, which is similar to what was found for

98

2,2'-bpy complexes. The remaining four sites on each Ni atom are composed
of water molecules. The Ni-O(water) bond distances are in the range of
2.044(3) — 2.063(3) A, which are similar to those found in complex 13. The
angle between the water molecules is 923°, which is greater than the O-Ni-
0 angle for complex 13.

(4) (2,2'-bPY)2Mn(CN)2 (16)'3H20.

The structure consists of a pseudo-octahedral Mnll atom coordinated to the N
atoms of two cis-2,2'-bpy ligands and two carbon atoms from the cyanide
ligand. The Mn-N(2,2'-bpy) bond lengths are in the range 2.2844(16) —
2.3503(17) A, whereas the Mn—C distances are 2.239(2) and 2.248(2) A. The

CEN bond lengths for the two cyanide ligand are 1.150(3) and 1.144(3) A

and the angle between the cyanide ligands is 96.92(8)°. The bite angles for
the 2,2'-bpy bidentate ligands are 7l.l9(6) and 71.26(6)°. Selected bond
distances and angles are presented in Table 2.10. Metrical parameters for the
similar compound (2,2'-bpy)2MnC12.2H20-CH3CH20H27 are Mn-N(2,2'-bpy)
at 2.275(3) and 2.287(3) A which are slightly shorter than in 16. The bite
angle for the 2,2'-bpy ligand is similar to the one found in 16 at 71.93(10)°.
The Mn-Cl bond distances are 2.4834(11) A. The angle between the chloride
atoms is slightly larger than what is expected for a perfectly octahedral

environment at 92.72(5)° due to the larger radii of the chloride atom.

99

(4) [(4,4'-(CH3)2-2i2'-bPY)2C0(CN)2l(PFo) (21)

1" atom coordinated to the N

The structure consists of a pseudo-octahedral Co
atoms of two cis-4,4'-(CH3)2-2,2'-bpy ligands and two carbon atoms from the
cyanide ligands. The asymmetric unit is composed of two [(4,4'-(CH3)2-2,2'-
bpy)2Co(CN)2]+ molecules, one of each isomer (A and A). The Co-N(4,4'-
(CH3)2-2,2'-bpy) bond lengths are in the range 1.875(15)-l.985(13) A,
whereas the Co-C distances are in the range 1.80(2)-l.882(18) A. The CEN
bond lengths are in the range 1.164(18)—1.20(2) A and the angle between the
cyanide ligands are 89.0(8)° and 91.9(8)°. The bite angles for 4,4'-(CH3)2-
2,2'-bpy bidentate ligands are 83.8(7)°, 83.6(5)°, 80.9(6)°, 84.1(7)°. Selected
bond distances and angles are presented in Table 2.11-2.12.

E. Magnetic Properties

Magnetic susceptibility studies were conducted to establish the ground state
spin values for the new paramagnetic molecular building blocks. The
magnetic moments at room temperature for the compounds are summarized
in Table 2.13. The magnetic susceptibility for the Mn11 center in [(2,2'-
bpym)2Mn(OH2)2](BF4)2 (1) leads to pet; and g values that are in good
agreement with the predicted spin-only values of 5.9 B.M. g ~ 1.9 (S = 5/2).

The complex, [(2,2'-bpym)2Co(OH2)2](BF4)2 (3), exhibits values of peg = 4.4

and g ~ 2.0. An octahedral, high-spin d7 Co" complex with s = 3/2 has a

100

Table 2.7. Selected bond distances [A] and angles [°] for

[Ni(2,2'-bPY)2(CH3CN)2](BF4)2 (7)-

 

 

 

 

Bond Distances
A B A-B [A]
Ni(l) N( 1) 2.077(3)
Ni(l) N(3) 2.079(3)
Ni(l) N (6) 2.091 (4
N(6) C(23) 1.142(5)
C(23) C(24) 1.453(5)
. Bond Angles
A B C A-B-C [°]
N(4) Ni( 1) N(3) 78.99(12)
N(2) Ni( 1) N(5) 171 .98(12)
N(3) N i( 1) N(5) 94.45(12)
N(l) Ni(l) N(5) 93.17(13)
N(6) Ni( 1) N(5) 84.15(14)
C(21) N(5) Ni(l) 167.1(3)
N(5) C(21) C(22) 178.7(5)

101

Table 2.8. Selected bond distances [A] and angles [°] for
(2,2'-bpy)2Mn(CF3803)2 (10)-

 

 

 

 

Bond Distances
A B A-B [A]

Mn(l) N(l) 2.2355(16)

Mn( 1) N(2) 2.2330(15)

Mn(l) 0(1) 2.1957(14)

8(1) 0(1) 1.4616(14)

S( 1) 0(2) 1.4330(16)

Bond Angles

A B C A-B-C [°]
N(l) Mn(l) N(2) 73.52(6)
0(1) Mn(l) N( l) 9074(6)
0(1) Mn( 1) N(2) 9764(5)
0(1A) Mn( 1) 0(1) 86.61(8)
Mn(l) 0(1) S(1) 137.10(9)

102

Table 2.9. Selected bond distances [A] and angles [°] for

[(2,2"bPY)2Ni(OH2)2](CF3SO3)2 (13)-

 

 

 

 

Bond Distances
A B A-B [A]
Ni(l) N(9) 2.064(2)
Ni(l) N(10) 2.086(2)
Ni(l) 0(5) 2.059(2)
N(6) 0(7) 2.061(2)
Bond Angles
A B C A-B-C [°]
N(4) Ni(l) N(9) 79.29(9)
N(8) Ni(l) N(lO) 78.89(9)
0(5) Ni(l) 0(7) 8455(9)
N (4) Ni(l) N(8) 9496(9)
0(5) Ni(l) N(10) 9390(9)
0(7) Ni(l) N(4) 91.01(9)

103

Table 2.10. Selected bond distances [A] and angles [°] for
[(2,2'-bpy)2Mn(CN)2] (16).

 

 

 

 

Bond Distances

A B A-B [A]
Mn(l) N(5) 2.3503(17)
Mn( 1) N(6) 2.2844( 16)
Mn(l) C( 1) 2.248(2)
Mn( 1) C(2) 2.239(2)
C(l) N(l) 1.150(3)

Bond Angles

A B C A-B-C [°]
N(3) Mn(l) N(4) 71 .26(6)
N (5) Mn( 1) N(6) 7 1 . 19(6)
N(3) Mn(l) C( 1) 8603(7)
N(3) Mn( 1) N(6) 9489(6)
C( 1) Mn( 1) C(2) 96.92(8)
Mn(l) C(l) N(l) 172.5(2)
Mn(l) C(2) N(2) 175.2(2)

104

Table 2.11. Selected bond distances [A] for [(4,4'-‘Bu-2,2'-bpy)2Co(CN)2]

 

 

(PFs) (21)-

A B A-B [A]
Co(1) N(l) 1.930(15)
Co(1) N(2) 1.919(16)
Co(1) N(3) 1.982(15)
Co(1) N(4) 1.946(13)
Co(1) C(37) 1.86(2)
Co(1) C(38) 1.865(19)
Co(2) N(7) 1.921(15)
Co(2) N (8) 1.875(15)
Co(2) N(9) 1.928(13)
Co(2) N( 10) 1.985(13)
Co(2) C(75) 1.882(18)
Co(2) C(76) 1 .80(2)
C(37) N (5) 120(2)
C(38) N(6) 1.197(19)
C(75) N(ll) 1.164(18)

 

105 .

Table 2.12. Selected bond angles [°] for [(4,4'-‘Bu-2,2'—bpy)2Co(CN)2](PF6)

 

 

(21).
A B C A-B-C [°]
N(l) Co(1) N(2) 84.1(7)
N (3) Co(1) N (4) 80.9(6)
N (7) Co(2) N(8) 83.8(7)
N(9) Co(2) N(lO) 83.6(5)
C(37) Co(1) C(38) 91 .9(8)
C(75) Co(2) C(76) 89.0(8)
Co(1) C(37) N(5) 175.1(18)
Co(1) C(38) N(6) 174.6(18)
Co(2) C(75) N(l 1) 174.3(17)
Co(2) C(76) N (12) 178.0(17)

 

106

 

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107

spin-only moment of peg = 3.87 B.M. for g = 2.28 The observed peg value
deviates from the predicted spin-only value due to spin-orbit coupling that is
typical of high-spin Co".28 The experimentally observed values are
consistent with literature reports of other octahedral Con compounds. The
complex, [(2,2'-bpym)2Ni(0H2)2](BF4)2 (4), exhibits a moment of peg = 2.7
B.M. with g ~2.0. The experimentally observed peg and g values deviate
only slightly from the predicted spin—only value of 2.83 B.M. and g = 2.

The magnetic susceptibility data for [(2,2'-bpy)2Mn(CH3CN)2](BF4)2 (5)
gave peg and g values of 5.9 B.M. g ~ 1.9. The compound [(2,2'-
bpy)2Co(CH3CN)2](BF4)2 (6), exhibits Heir = 4.0 and g ~ 2.0. The complex
[(2,2'-bpy)2Ni(CH3CN)2](BF4)2 (7), exhibits a moment of Meir = 3.25 B.M.
with g ~2.0. These values deviate slightly from the predicted spin-only value
of 2.83 B.M. and g = 2, but are consistent with literature reports of other
octahedral NilI compounds.28 The magnetic susceptibility data for the high-
spin S = 5/2 Mn'I center in (2,2'-bpy)2Mn(CF3S03)2 (10) and
(phen)2Mn(CF3803)2 (12) gave peg and g values that are in good agreement
with the predicted spin-only values of 5.9 B.M. and 6.0 B.M. with g ~1.9
respectively. The moment for [(2,2'-bpy)2Ni(0H2)2](CF3803); (13), is 3.0
B.M. with g ~2.0. The experimentally observed peg and g values deviate

from the predicted spin- only value of 2.83 B.M. and g = 2. The

108

experimental moment of the low-spin d7 ColI complex, [(2,2'-bpy)2Co(CN)2]
(17), with S = 1/2 is [Jeff = 2.54 with a g = 2.91. The observed p.65 value
deviates from the predicted spin-only values due to spin-orbit coupling.

4. SUMMARY AND CONCLUSIONS

The compounds (2,2'-bpy)2MC12 undergo chloride abstraction to yield the
cis-[(2,2'-bpy)2M(S)2]2+, solvated precursors. These precursors are obtained
in good yield whereas the cis-[(2,2'-bpym)2M(0H2)2](BF4)2 complexes are
prepared in a much lower yield. Attempts to synthesize an iron(II) precursor
with either 2,2'-bpym or 2,2'-bpy yielded only a mixture of FeII and Fem.
The dicyanide species, (2,2'-bpy)2M(CN)2 (M = MnII and Co"), prepared by
the water/methanol are crystalline. The trivalent chloride precursors were
synthesized in good yield, but further synthetic work needs to be carried out
to prepare the trivalent cyanide precursors. Silver cyanide is not a good
choice for introducing cyanide into a reaction since its solubility is low. The
successful synthesis of several divalent and trivalent precursors provides an
opportunity to explore different charges for the resulting molecular squares.
The molecular squares will be cationic, but the charge can be reduced if
trivalent cyanide precursors are successfully synthesized. The self-assembly
reactions of the two types of precursors were investigated. Based on infrared

spectrOSCOpic data, the most promising of these reactions is the 1:1 reaction

109

of [(2,2'-bpy)2Co(CN)2] (l7) and [(2,2'-bpy)2Mn(CF3SO3)2] (10) which led

to a product with a single strong cyanide stretch in the infrared spectrum.

110

5. REFERENCES

1. Dunbar, K. R.; Heintz, R. A. Prog. Inorg. Chem. 1997, 45, 283.

2. Holtzaman, H. Ind. Eng. Chem. 1945, 37, 855.

3. (a) Ito, A.; Suenaga, M.; Ono, K. J. Chem. Phys. 1968, 48(8), 3597. (b)
Chappert, J .; Sawicka, B.; Sawicki, J. Phys. Stat. Sol. 1975, B72, K139.

4. (a) Hatlevik, 0; Buschmann, W. B.; Zhang, J.; Manson, J. L.; Miller, J. S.
Adv. Mater. 1999, II, 914. (b) Ferlay, S; Mallah, T.; Ouahés, R; Veillet, P;
Verdaguer, 1995, 378, 701. (c) Holmes, S. M.; Girolami, G. S. J. Am.
Chem. Soc. 1999, 121, 5593.

5. (a) Ohba, M.; Maruono, N.; Okawa, H; Enoki, T.; Latour, J. M. J. Am.
Chem. Soc. 1994, 116, 11566. (b) Ohba, M.; Okawa, H.; Ito, T.; Ohto, A. J.
Chem. Soc., Chem. Commun. 1995, 1545. (c) Ohba, M.; Fukita, N.; Okawa,
H. J. Am. Chem. Soc. 1997, 119, 1011. (d) Fukita, N.; Ohba, H.; Okawa, H.;
Matsuda, K.; Iwamura, H. Inorg. Chem. 1998, 37, 842.

6. Kalb, W. C.; Demidowicz, Z.; Speckman, D. M.; Knobler, C.; Teller, R.
G.; Hawthorne, M. F. Inorg. Chem. 1982, 21, 4027.

7. Martinez, J.; Adams, H.; Bailey, N. A.; Maitlis, P. M. J. Organamet.
Chem. 1991, 405, 393.

8. (a) Fujita, M.; Yazaki, J.; Ogura, K. J. Am. Chem. Soc. 1990, 112, 5645.

(b) Fujita, M.; Ibukura. F.; Hagihara, H.; Ogura, K. Nature 1994, 367, 720.

111

(c) Stang, P. J .; Cao, D. H. J. Am. Chem. Soc. 1994, 116, 4981. (d) Olenyuk,
B.; Whiteford, J. A.; Stang, P. J. J. Am. Chem. Soc. 1996, 118, 8221. (e)
Blake, A. J.; Hill, S. J.; Hubberstey, R; Li, W.-S. J. Chem. Soc. Dalton
Trans. 1997, 913. (f) Baxter, P. N. W.; Lehn, J.-M.; Kneisel, B. 0.; Fenske,
D. Chem. Commun. 1997, 2231. (g) Stang, P. J.; Olenyuk, B. Acc. Chem.
Res. 1997, 30, 502. (h) Olenyuk, B.; Fechtenktter, A.; Stang, P. J. J. Chem.
Soc., Dalton Trans. 1998, 1707. (i) Constable, E. C.; Schofield, E. Chem.
Commun. 1998, 403. (i) Fujita, M.; Aoyagi, M.; Ibukura, F.; Pgura, K.;
Yamaguchi, K. J. Am. Chem. Soc. 1998, 120, 611. (k) Boyle, P. D.; Cross,
W. I.; Godfrey, S. M.; McAuliffe, C. A.; Pritchard, R. G.; Sarwar, 8.;
Sheffield, J. M. Angew. Chem. Int. Ed. 2000, 39, 1796. (l) Rajendran, T.;
Manimaran, B.; Lee, F.-Y.; Lee, G.-H.; Peng, S.-M.; Wang. C. M.; Lu, K.-L.
Inorg. Chem. 2000, 39, 2016. (m) Sugiura, K.-I.; Fujimoto, Y.; Sakata, Y.
Chem. Commun. 2000, 1105. (n) Schnebeck, R.-D.; Freisinger, B.; Lippert,
B. Eur. J. Inorg. Chem. 2000, 1193.

9. Oshio, H.; Tamada, 0.; Onodera, H.; Ito, T.; Ikoma, T.; Tero-Kubota, S.
Inorg. Chem. 1999, 38, 5686.

10. Edited by Brauer, G. Handbook of Preparative Inorganic Chemistry
1965, 2, second edition, Academic Press New York: London.

11. Fort, Y.; Becker, 8.; Caubere; P. Tetrahedron 1994, 50, 11893.

112

12. Badger, G. M.; Sasse, W. H. F. J. 1956, 616.

13. Kern, R. J. J. Inorg. Nucl. Chem. 1962, 24, 1105.

14. Hiskey, M. A.; Ruminski, R. R. Inorg. Chim. Acta 1986, 112, 189.

15. Harris, C. M.; McKenzie, E. D. J. Inorg. Nucl. Chem. 1967, 29, 1047.

16. Morcom, R. E.; Bell, C. F. J. Inorg. Nucl. Chem. 1973, 35, 1865.

17. Saint 1000 and 6.0, Bruker Analytical X-ray Instruments, Madison, WI
53719 (1999 and 2000)

18. Sheldrick, G. M. “SADABS, Siemens Area Detector Absorption
Correction”, Univ. of Gottingen, Gottingen, Germany (1998).

19. Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.; Giacovazza,
C.; Guagliardi, A.; Molitemi, A. G. G.; Polidori, G.; Spagna, R. J. Appl.
Crystallogr. 1999, 32, 115.

20. Sheldrick, G. M. SHELXTL version 5.10, Reference Manuel, Bruker
Industrial Automation, Analytical Instrument, Madison, WI 53719 (1999).
Program for Refinement of Crystal Structure, University of thtingen,
Gdttingen, Germany.

21. McKenzie, E. D. Coord. Chem. Rev. 1971, 6, 187.

22. (a) Julve, M.; Verdaguer, M.; De Munno, G.; Real, J. A.; Bruno, G.
Inorg. Chem. 1993, 32, 795. (b) Andrés, B.; De Munno, G.; Julve, M.; Real,

J. A.; Lloret, F. J. Chem. Soc. Dalton Trans. 1993, 2169. (c) De Munno, G.;

113

Julve, M.; Lloret, F.; Faus, J .; Caneschi, A. J. Chem. Soc. Dalton Trans.
1994, 1175. (d) De Munno, G.; Poerio, T.; Viau, G.; Julve, M.; Lloret, F.;
Joumaux, Y.; Riviere, E. Chem. Commun. 1996, 2587. (e) De Munno, G.;
Arrnentano, D.; Julve, M.; lloret, F.; Lescouézec, R.; Faus, J. Inorg. Chem.
1999, 38, 2234.

23. Strukl, J. S.; Walter, J. L. Spectrochim. Acta 1971, 27A, 223.

24. (a) Lawrance, G. A. Chem. Rev. 1986, 86, 17. (b) Boumizane, K.;
Herzog-Cance, M. H.; Jones, D. J.; Pascal, J. L.; Potier, J.; Roziere, J.
Polyhedron 1991, 10, 2757.

25. Decurtins, S.; Schmalle, H. W.; Schneuwly, P.; Zheng, L.-M. Acta Cryst.
1996, C52, 561.

26. De Munno; G.; Julve, M.; Lloret, F.; Derory, A. J. Chem. Soc. Dalton
Trans. 1993, 1179.

27. McCann, S.; McCann, M.; Casey, M. T.; Jackman, M.; Devereux, M.;
McKee, V. Inorg. Chim. Acta 1998, 279, 24.

28. (a) Carlin, R. L. Magnetochemistry, Springer-Verlag Berlin Heidelberg
1986. (b) Mabbs, F. B.; Machin, D. J. Magnetism and Transition Metal

Complexes, London Chapman and Hall 1973.

114

Chapter 111

Molecular Cube Precursors and Reactivity Studies

115

1. INTRODUCTION

The well-known material Prussian Blue, Fe4m[Fe"(CN)6]-xH20 is readily
prepared by addition of [Fe"(CN)6]4' to [Fem(H20)g]3+ in water. The three-
dimensional structure adopted by this compound is based on a simple face-
centered cubic arrangement of alternating metal atoms M and M' connected
by cyanide.l One possible way to limit the growth of the 3-D phase is to use
trigonal capping ligands to protect one side of the metal ion. In this way, the
building blocks fac—[L3M(CN)3]"' and fac—[L3M(S)3]n+ can be used to build
cubes as depicted in Figure 3.1. A discrete molecular cube with cyanide
edges was synthesized by Rauchfuss and co-workersz, who prepared the
tn'cyanide precursor, [EtaN]3[CpRh(CN)3], and reacted it with (n6-
C61-13Me3)Mo(C0)3 in the presence of alkali metal cations to form
[Et4N]3{M[Cp*Rh(CN)3]4[Mo(C0)3]4} (M = K or Cs) (Figure 1.8.). The
cube contains twelve external C0 and four C5Me5 ligands. In addition, the

3 which, when

same group has synthesized other tricyanide precursors
combined with non-cyanide complexes, lead to molecular geometries other
than a cube. Another group working in this area, namely that of Long and
co-workers, has reported the crystal structures of two molecular cubes 4

based on the tricyanide precursor, [(tacn)Co(CN)3] tacn = 1,4,7-

triazacyclononane. These are [Cr4Co.,(CN)12(tacn)g]12+ and

116

[C03(CN)12(taCII)3]12+. The homometallic cobalt(III) cube was characterized
by single crystal X-ray crystallography whereas the mixed metal analogue
was characterized by positive ion electrospray mass spectrometry.

It should be obvious from the previous discussion, that in order to design
a convergent synthesis of molecular cubes from octahedral metal ions, one
must cap three coordination sites with one facial tridentate ligand that leaves
three mutually orthogonal sites free for substitution chemistry as indicated in
Figure 3.1. Possible choices for tridentate, facially capping ligands are tris-
pyrazolylborate (Tp), diethylenetriamine (dien), 1,4,7-triazacyclononane
(tacn) and 1,4,7-trithiacyclononane (983). The second building block must
also be a precursor that is tailored to have three sites blocked by an innocent
capping ligand but, in this case, the other three sites are occupied by three
cyanide ligands at 90° from one another. One can envisage that the reaction
between foe-[(L3)M(S)3]“+ and fac-[(L3)M'(CN)3] can either yield a
molecular cube, a part of a cube, or any number of open polymeric species
depending on the kinetics and thermodynamics of the reaction. In this
chapter, the preparation and characterization of the two different types of

precursors are presented and discussed. The main point of this thesis, in

117

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contrast to the work of Rauchfuss where diamagnetic metal ions are used, is

to use two different paramagnetic metal ions M and M' to build mixed metal

[M4M'4(CN)12(L3)3]“+/"' clusters with high spin ground states.

2. EXPERIMENTAL

A. PHYSICAL MEASUREMENTS

Infrared spectra were recorded on a Nicolet 42 spectrophotometer in the
Chemistry Department at Michigan State University or on a Nicolet 470
instrument in the Chemistry Department at Texas A&M University. Infrared
spectra were recorded at 4 cm'1 resolution and 32 scans unless otherwise
stated. Solid samples were measured as KBr pellets or Nujol mulls on KBr
or CsI plates. Elemental analyses were performed at Desert Analytics,
Tucson, AZ or in the Chemistry Department at Michigan State University on
a Perkin and Elmer Series II CHNS/O analyzer 2400. Magnetic
measurements were performed on a Quantum Design MPMS-S instrument
equipped with a SQUID sensor housed in the Physics and Astronomy
Department at Michigan State University or a MPMS-XL SQUID

magnetometer located in the Chemistry Department at Texas A&M

University.

119

B. SYNTHESES

The starting materials [M(CH3CN)6]X2 (M = Fe", Co", Ni", and x = (BF4)',
(CF3SO3)', (PF6)‘) were synthesized according to literature methods.6 The
metal complexes and ligands, CoClz, FeCl3, KCN, [EtaN]CN, 1,4,7-
trithiacyclononane (983) and diethylenetriamine (dien), were purchased
from Aldrich and used without further purification. Sodium tris-
pyrazolylborate, Nan, was prepared according to literature methods.7 Silver
hexafluorophosphate, silver tetrafluoroborate, silver nitrate and silver triflate
were purchased from either Strem or Aldrich, and used without further
purification. Acetone and acetonitrile were distilled over 3 A sieves.
Benzene, diethyl ether, THF and toluene were distilled over sodium-
potassium/benzophenone, whereas methylene chloride was distilled over
P205 under a nitrogen atmosphere. Methanol and ethanol were dried over
magnesium alkoxide. Unless otherwise specified, all reactions were carried
out under a nitrogen atmosphere using standard Schlenk-line techniques.

(1) Preparation of [TpFe(CH3CN)3](CF3SO3) (22).

One equivalent of Nan (0.137 g, 0.582 mmol) in 30 mL of methanol was
added via cannula techniques to a methanol solution (20 mL) of
[Fe(CH3CN)6](CF3SO3)2 (0.289 g, 0.482 mmol). Upon addition of the Nan

reagent, an immediate change in color ensued from colorless to red. The

120

reaction was left to stir for 12 h, after which time the solution was reduced in
volume to ~10 mL and allowed to stand overnight in the refrigerator. A crop
of colorless crystals of Na(CF3SO3) was removed by filtration in an inert
atmosphere. The remaining red solution was treated with 40 mL of diethyl
ether to yield a red product. The diethyl ether was removed by cannula
techniques, and red solid was dried in vacuo. Yield: (0.193 g, 74%). IR data
(Nujol, cm’l): 2480 (w), 2312 (m), 2284 (m), 2264 (w), 1504 (m), 1406 (m),
1307 (s), 1271 (s), 1242 (s), 1230 (s), 1209 (s), 1170 (s), 1115 (m), 1047 (8,
br), 978 (m), 798 (m), 767 (m), 636 (m), 522 (m).

(2) Preparation of K[TpFe(CN)3] (23).

Three equivalents of KCN (0.736 g, 11.32 mmol) in 50 mL of methanol
were added via cannula techniques to a 50 mL methanol solution of
Na[TpFeCl3] (1.50 g, 3.78 mmol) over a 1 h period. The reaction was stirred
for 12 h, after which time the by-product KC] was removed by filtration
under an inert atmosphere and trapped in Celite. The resulting red filtrate
was reduced in volume to ~5-10 mL, and treated with 40 mL of diethyl ether
to precipitate a red product. The diethyl ether was removed by cannula
techniques, and the red solid was dried in vacuo. Yield: (0.654 g, 53%) IR
data (Nujol, cm'l): 2490 (w), 2118 (w), 2054 (w), 2035 (m), 1408 (w), 1311

(m), 1261 (m), 1215 (m), 1153 (w), 1111 (m), 1072 (w), 1047 (m), 798 (m),

121

750 (w).
(3) Preparation of [TpCo(CH3CN)3]X ( X = (BE) (24) , (CF3SO3)' (25),
(PFJ (27))-
Preparation of [TpCo(CH3CN)3](BF4) (24).
An acetonitrile solution (20 mL) of Nan (0.148 g, 0.628 mmol) was added
via cannula techniques to an acetonitrile (20 mL) solution of
[Co(CH3CN)6](BF4)2 (0.301 g, 0.628 mmol). The solution, which gradually
turned more orange in color, was stirred for 12 h, after which time the
solution was reduced in volume to about 10 mL and placed overnight in the
freezer at 0 °C. The solution was then filtered under an inert atmosphere to
remove the crystalline NaBF4, and washed with cold CH3CN (2 x 10 mL).
The solution was reduced to ~5—10 mL and treated with 40 mL of diethyl
ether to precipitate an orange product. The diethyl ether was removed by
cannula techniques, and the orange solid was dried in vacuo. Yield: (0.253 g,
84%) IR data (Nujol, cm‘l): 2517 (w), 2487 (w), 2314 (m), 2287 (m), 1732
(m), 1504 (m), 1406 (m), 1309 (s), 1261 (s), 1213 (s), 1112 (s), 1074 (s),
1047 (3, br), 1029 (s), 981 (m), 939 (w), 890 (w), 873 (w), 800 (s), 770 (m),
663 (m), 622 (w), 551 (w), 525 (w), 518 (w), 466 (w), 454 (w), 440 (w).

Preparation of [TpCo(CH3CN)3](CF3SO3) (25).

122

An acetonitrile solution (20 mL) of Nan (0.118 g, 0.500 mmol) was added
via cannula techniques to an acetonitrile (20 mL) solution of
[Co(CH3CN)6](CF3SO3)2 (0.301 g, 0.500 mmol). The solution gradually
turned more orange in color. The reaction was stirred for 12 h, after which
time the solution was reduced in volume to ~10 mL and placed in the
refrigerator overnight. The solution was then filtered under an inert
atmosphere to remove crystalline Na(CF3S03) and washed with cold CH3CN
(2 x 5 mL). The solution was reduced in volume to ~5 mL, and 40 mL of
diethyl ether were added to precipitate an orange product. The diethyl ether
was removed by cannula techniques, and the orange solid was dried in
vacuo. Yield: (0.173 g, 64%) IR data (Nujol, em“): 2509 (w), 2477 (m),
2314 (m), 2285 (m), 2264 (w), 1504 (m), 1404 (m), 1309 (s), 1265 (s, br),
1228 (s), 1211 (s), 1153 (s), 1113 (s), 1068 (w), 1047 (s), 1032 (s), 978 (m),
938 (w), 927 (w), 891 (w), 810 (w), 797 (w), 785 (m), 760 (m), 726 (m), 663
(m), 636 (s), 620 (m), 584 (w), 574 (m), 516 (m).

Preparation of [TpCo(CH3CN)3](PF6) (26).

One equivalent of Nan (0.072 g, 0.307 mmol) in 20 mL of acetonitrile was
added via cannula techniques to an acetonitrile (20 mL) solution of
[Co(CH3CN)6](PF6)2 (0.182 g, 0.338 mmol). The solution, which gradually

turned more orange in color, was stirred for 12 h, after which time the

123

solution was reduced in volume to ~10 mL and placed in the refrigerator
overnight. The solution was then filtered in an inert atmosphere to remove
the crystalline NaPF6 by-product and washed with cold CH3CN (2 x 5 mL).
The solution was reduced to ~5 mL, and 40 mL of diethyl ether were added
to precipitate an orange product. The diethyl ether was removed by cannula
techniques, and the orange solid was dried in vacuo. Yield: (0.120 g, 66%)
IR data (Nujol, cm'l): 2474 (m), 2316 (m), 2287 (m), 1506 (m), 1404 (w),
1307 (m), 1213 (m), 1115 (m), 1070 (w), 1047 (m), 978 (m), 839 (s), 752
(m), 715 (m), 665 (m), 619 (m), 559 (m).

(4) Preparation of [Et4N]2[TpCo(CN)3] (27).

Three equivalents of [EtaN]CN (0.297 g, 1.91 mmol) dissolved in 40 mL of
acetonitrile were added via cannula techniques over a 2 h period to an
acetonitrile solution (40 mL) of [TpCo(CH3CN)3](PF6) (0.339 g, 0.629
mmol). The color of the solution turned green then blue before reverting
back to an orange color. The reaction was stirred for 12 h, after which time
the solution was reduced in volume to ~10-15 mL and placed in the
refrigerator overnight. The solution was filtered to remove the crystalline
[Et4N]PF6 by-products and washed with cold CH3CN (2 x 10 mL) in an inert
atmosphere. The solution was reduced in volume to ~5 mL and treated with

50 mL diethyl ether to precipitate an orange product. The diethyl ether was

124

removed by cannula techniques, and the orange solid was dried in vacuo.
Yield: (0.298 g, 78%). IR data (Nujol, cm'l): 2511 (w), 2428 (w), 2127 (m),
2112 (m), 1404 (m), 1309 (m), 1294 (m), 1259 (w), 1211 (m), 1186 (m),
1172 (m), 1115 (m), 1078 (m), 1046 (m), 1037 (m), 1003 (m), 976 (w), 960
(w), 923 (w), 880 (m), 839 (s), 787 (m), 762 (m), 727 (m), 669 (w), 629 (w),
559 (m), 408 (m).
(5) Preparation of [TpNi(CH3CN)3]X ( X = (BE) (28), (CF;SO3)' (29),
(PF t)’ (30))-
Preparation of [TpNi(CH3CN)3](BF4) (28).
One equivalent of Nan (0.254 g, 1.08 mmol) dissolved in 40 mL of
acetonitrile was added via cannula techniques to an acetonitrile (40 mL)
solution of [Ni(CH3CN)6](BF4)2 (0.515 g, 1.08 mmol). The solution
gradually turned pale-purple in color. The reaction was stirred for 12 h, after
which time the solution was reduced in volume to ~10 mL and placed in the
freezer for at least 12 h. The solution was then filtered in an inert atmosphere
to remove crystalline NaBF4 by-product and washed with cold CH3CN (2 x
10 mL). The solution was reduced to ~5-10 mL and treated with 40 mL of
diethyl ether to precipitate a purple product. The diethyl ether was removed
by cannula techniques, and the purple solid was dried in vacuo. Yield:

(0.455 g, 88%) IR data (Nujol, cm’l): 2476 (m), 2314 (m), 2296 (m), 1504

125

(m), 1408 (m), 1396 (m), 1311 (s), 1261 (w), 1213 (s), 1111 (s), 1047 (s, br),
983 (m), 936 (w), 893 (w), 815 (w), 798 (m), 783 (m), 765 (m), 756 (m),
746 (m), 726 (m), 665 (m), 623 (m), 552 (w), 525 (w), 519(w).

Preparation of [TpNi(CH3CN)3](CF3SO3) (29).

An acetonitrile solution (40 mL) of Nan (0.119 g, 0.506 mmol) was added
via cannula techniques to an acetonitrile (40 mL) solution of
[Ni(CHgCN)6](CF3SO3)2 (0.305 g, 0.506 mmol). The solution gradually
turned pale purple in color. The reaction was stirred for 12 h, after which
time the solution was reduced in volume to ~10 mL and placed in the freezer
at 0 °C for at least 12 h. The solution was filtered to the remove crystalline
NaOTf by-product and washed with cold CH3CN (2 x 5 mL) under an inert
atmosphere. The solution was reduced to ~5 mL and treated with 40 mL of
diethyl ether to effect the precipitation of a purple product. The diethyl ether
was removed by cannula techniques, and the purple solid was dried in
vacuo. Yield: (0.237 g, 86%) IR data (Nujol, cm"): 2474 (m), 2467 (m),
2318 (m), 2309 (m), 2291 (m), 2284 (m), 2264 (m), 1504 (w), 1423 (w),
1410 (m), 1398 (m), 1311 (s), 1273 (s, br), 1259 (s, br), 1230 (s), 1211 (s),
1184 (m), 1155 (m, br), 1113 (m), 1093 (w), 1076 (m), 1047 (s), 1032 (s),
982 (m), 940 (w), 927 (w), 791 (m), 771 (m), 763 (s), 755 (m), 745 (m), 724

(m), 663 (m), 642 (s), 638 (s), 622 (m), 584 (w), 574 (w), 520 (m), 464 (w),

126

452 (w), 438 (w).

Preparation of [TpNi(CH3CN)3](PF6) (30).

One equivalent of Nan (0.122 g, 0.520 mmol) in 40 mL of acetonitrile was
added via cannula techniques to an acetonitrile (40 mL) solution of
[Ni(CH3CN)5](PF6)2 (0.323 g, 0.543 mmol). The solution gradually turned
pale purple in color. The reaction was stirred for 12 h, after which time the
solution was reduced in volume to ~10 mL and placed in the refrigerator
overnight. The solution was filtered to remove the crystalline NaPF6 by-
product and washed with cold CH3CN (2 x 10 mL) in an inert atmosphere.
The solution was reduced to ~5-10 mL, and 40 mL of diethyl ether were
added to precipitate the purple product. The diethyl ether was removed by
cannula techniques, and the purple solid was dried in vacuo. Yield: (0.250 g,
85%) IR data (Nujol, em"): 2478 (m), 2318 (m), 2291 (m), 1630 (m), 1504
(m), 1404 (s), 1311 (s), 1213 (s), 1149 (m), 1113 (s), 1070 (m), 1047 (s),
979 (m), 833 (3, br), 788 (m), 752 (s), 727 (m), 663 (m), (m), 559 (s).

(6) Preparation of Nisz (32).

Two equivalents of Nan (0.099 g, 0.422 mmol) dissolved in 20 mL of
acetonitrile were added via cannula techniques over a 10 min period to an
acetonitrile solution of [Ni(CH3CN)6](BF4)2 (0.100 g, 0.210 mmol). The

reaction stirred for 12 h, after which time a pink precipitate was present in a

127

pale pink solution. The solution was removed via cannula techniques, and
the precipitate was washed with acetonitrile (2 x 10 mL) followed by diethyl
ether (2 x 20 mL). The diethyl ether was removed by cannula techniques,
and the pale pink solid was dried in vacuo. Yield: (0.043 g, 43%). IR (Nujol,
cm'l): 2476 (m), 1502 (m), 1423 (w), 1404 (m), 1394 (m), 1309 (s), 1211
(s), 1109 (s), 1047 (s), 1030 (s), 976 (m), 881 (w), 790 (w), 765 (w), 754 (s),
746 (s), 727 (m), 667 (m), 640 (w), 621 (m), 550 (w), 526 (w), 518 (w).

(7) Preparation of [(9S3)C0(CH3CN)3](PF6)2 (32).

One equivalent of 983 (0.130 g, 0.726 mmol) dissolved in 15 mL of
dichloromethane was slowly added to a 15 mL dichloromethane solution of
[Co(CH3CN)6](PF6)2 (0.431 g, 0.726 mmol) over a 10-15 min period under
an inert nitrogen atmosphere. The color of the solution gradually turned
more orange and a bit pinkish (salmon). When the volume of the solution
was ~10 mL, the addition of 40 mL of diethyl ether produced an orange/pink
product, which was collected by filtration. The product is soluble in most
common solvents. Yield: (0.289 g, 61%) IR data (Nujol, cm‘l): 1480 (s),
1410 (m), 1364 (m), 1340 (w), 1312 (m), 1301 (w), 1260 (w), 1186 (m),
1170 (w), 1153 (w), 1078 (m), 1033 (m), 105 (m), 937 (w), 881 (s), 835 (5,

br), 794(8), 789 (s), 668 (w), 557 (s), 467 (w).

128

(8) Preparation of (9S3)COCI; (33).

One equivalent of 983 (0.257 g, 1.43 mmol) dissolved in 25 mL of
acetonitrile was reacted with CoClz (0.199 g, 1.53 mmol) in 25 mL of
acetonitrile. A navy precipitate was observed to form immediately. The
reaction was stirred for 12 h under an inert nitrogen atmosphere, after which
time a navy precipitate and pale green solution were observed to be present.
The precipitate was collected by filtration and washed with 20 mL of diethyl
ether. The pale green solution was discarded. Yield: (0.44 g, 94%) IR data
(Nujol, cm'l): 2279 (w), 2244 (w), 1439 (s), 1410 (s), 1396 (m), 1366 (m),
1286 (m), 1274 (w), 1247 (w), 1182 (m), 1131 (w), 1120 (w), 1041 (m),
1014 (w), 937 (m), 917 (w), 904 (s), 825 (s), 820 (m), 690 (m), 669 (m), 635
(w), 623 (m), 488 (m), 449 (m).

(9) Preparation of [Co(9S3)2]C12 (34).

Two equivalents of 983 (0.279 g, 1.55 mmol) dissolved in 25 mL of
acetonitrile were combined with C00; (0.100 g, 0.769 mmol) in 25 mL of
acetonitrile which led to the immediate precipitation of a navy product. The
reaction was allowed to stir for ~12 h under an inert nitrogen atmosphere
after which time a navy precipitate and a pale red/pink solution were present.
The precipitate was collected by filtration and washed with 20 mL of diethyl

ether. The red/pink solution was discarded. Yield: (0.125 g, 33%). IR data

129

(Nujol, cm'l): 1455 (m), 1441 (m), 1405 (m), 1346 (m), 1295 (m), 1279 (m),
1260 (m), 1172 (m), 1141 (m), 1097 (m), 1016 (s), 936 (m), 902 (s), 870
(w), 820 (s), 803 (s), 794 (s), 688 (m), 668 (w), 631 (m), 623 (m), 490 (m),

447 (m), 395 (m).

3. REACTIVITY STUDIES

(1) Reaction of [TpFe(CH3CN)3](CF3SO3) with K[TpFe(CN)3].

A solution of [TpFe(CH3CN)3](CF3SO3) (0.107 g, 0.197 mmol) dissolved in
20 mL of methanol was slowly added via a cannula to a 20 mL methanol
solution of K[TpFe(CN)3] (0.076 g, 0.196 mmol) over a 15 min period. A
green precipitate formed immediately in an orange/red solution. The
orange/red solution was separated from the green solid and transferred to
another flask where it was reduced in volume to 10 mL, at which point it
was treated with 40 mL of diethyl ether to precipitate an orange/red product.
The diethyl ether was removed by cannula techniques and the orange/red
solid was dried in vacuo. IR data for the orange/red solid (Nujol, cm'l): 2474
(w), 1504 (w), 1406 (m), 1307 (m), 1296 (s), 1248 (s), 1204 (m), 1180 (m),
1113 (m), 1047 (s), 979 (w), 763 (m), 740 (w), 659 (m), 648 (m), 520 (m).
The green precipitate was washed with 20 mL of diethyl ether and dried in
vacuo. The amount of green precipitate was negligible ~ 0.009 g. IR data for

the green precipitate (Nujol, cm'l): 2090 (m), 2066 (m), 1572 (w), 1410 (w),

130

1261 (m), 1215 (m), 1113 (m), 1041 (s), 800 (m), 754 (w), 642 (w), 621 (w),
466 (w).

(2) Reaction of [EtaN]2[TpCo(CN)3] with [(dien)Ni(NO3)2].

A 10 mL acetonitrile/15 mL methanol solution of [(dien)Ni(NO3)2] (0.113 g,
0.395 mmol) was added via a cannula to a 10 mL acetonitrile/ 15 mL
methanol solution of [Et4N]2[TpCo(CN)3] (0.168 g, 0.275 mmol). After 30
min, a green precipitate formed in a colorless solution. The green precipitate
was removed by filtration and washed with 10 mL of diethyl ether. IR
(Nujol, cm'l): 3358 (s), 3290 (s), 3171 (w), 2164 (s), 1647 (m), 1595 (s),
1406 (m), 1309 (s), 1215 (m), 1169 (w), 1111 (w), 1041 (s), 979 (m), 889
(w), 843 (s), 773 (w), 738 (w), 557 (m), 443 (m).

(3) Reaction of [Et4N13[(C0)3M0(CN)3] with [(983)C0(CH3CN)3](PF6)2
An excess of [(9S3)Co(CH3CN)3](PF6)2 (0.270 g, 0.414 mmol) dissolved in
25 mL acetonitrile was reacted dropwise with [EtaN]3[(CO)3Mo(CN)3]
(0.110 g, 0.212 mmol) in 25 mL of acetonitrile. The reaction was stirred for
12 h, at which point a black precipitate in an orange solution was observed
to be present. The black precipitate was removed by filtration and washed
with 10 mL of diethyl ether. The orange filtrate was reduced to ~10 mL at
which point 40 mL of diethyl ether were added to precipitate an orange

product. The diethyl ether was decanted and the orange product was dried in

131

vacuo. The IR data of the orange solid was identical to the IR spectrum of
the cobalt starting material. IR data (Nujol, cm'l): 2310 (w), 2284 (w), 2248
(w), 2098 (3, br), 2027 (s), 1888 (8, br), 1792 (3, br), 1635 (8, br), 1287 (8,
br), 1170 (m), 1021 (m, br), 936 (m), 902 (m), 843 (s), 622 (w), 597 (m),
557 (w), 446 (m), 404 (m).

(4) Reaction of [EtaN]3[(CO)3Mo(CN)3] with (THF)3CrCl3.

An excess of (THF)3CrCl3 (0.245 g, 0.654 mmol) dissolved in 25 mL of
acetonitrile was added dropwise to a 20 mL acetonitrile solution of
[EtaN]3[(CO)3Mo(CN)3] (0.171 g, 0.330 mmol) for 15 min. The solution,
which turned red immediately, was stirred for 12 h, reduced in volume and
treated with 40 mL of diethyl ether to precipitate a red product. The diethyl
ether was removed by cannula techniques and the red solid was dried in
vacuo. IR data (Nujol, cm'l): 2318 (w), 2288 (w), 2240 (w), 2101 (s), 1995
(s), 1876 (3, br), 1760 (8, br), 1649 (m), 1572 (m), 1361 (s), 1301 (m), 1179
(m), 1171 (s), 1113 (w), 1076 (w), 1064 (w), 1051 (w), 1029 (w), 999 (m),
953 (w), 917 (w), 890 (w), 846 (w), 821 (w), 782 (m), 735 (w), 627 (w), 599
(m, sh), 546 (m), 489 (m, br), 387 (w), 323 (m), 315 (m), 308 (m), 302 (m),
287 (w), 275 (w), 260 (w), 254 (w), 245 (w), 233 (w), 227 (m), 219 (m), 211
(w), 206 (m), 202 (m).

(5) Reaction of [EtaN]3[(CO)3Mo(CN)3] with Na[TpCrCl3].

132

Greater than a two-fold excess of Na[TpCrCl3] (0.184 g, 0.491 mmol)
dissolved in 25 mL acetonitrile was added dropwise over a 15 min period to
a 25 mL acteonitrile solution of [EtaN]3[(CO)3Mo(CN)3] (0.121 g, 0.233
mmol). The resulting red solution was stirred for 12 h, after which time it
was reduced in volume and treated with 40 mL of diethyl ether to precipitate
a red product. The diethyl ether was removed by cannula techniques and the
red solid was dried in vacuo. IR data (Nujol, cm’l): 2096 (m), 2073 (m),
1996 (w), 1946 (w), 1883 (m), 1782 (m, br), 1702 (w), 1634 (w), 1618 (w),
1576 (w), 1500 (w), 1405 (m), 1310 (m), 1261 (w), 1210 (m), 1181 (w),
1170 (m), 1154 (w), 1115 (w), 1097 (w), 1074 (w), 1050 (m), 1000 (m), 889
(w), 843 (w), 818 (w), 771 (m), 659 (w), 621 (w), 598 (w), 545 (w), 491 (w).
(6) Reaction of [EtaN]3[(CO)3Mo(CN)3] with [(dien)Ni(NO3)2].

A slight excess of [(dien)Ni(NO3)2] (0.082 g, 0.287 mmol) dissolved in 25
mL of methanol was added dropwise for 15 min to a 25 mL methanol
solution of [EtaN]3[(CO)3Mo(CN)3] (0.127 g, 0.245 mmol) which effected
an instantaneous formation of a yellow precipitate in a pale yellow solution.
The reaction was stirred for 12 h, after which time the yellow precipitate was
collected by filtration and washed with 10 mL of diethyl ether. The pale
yellow solution was combined with KPF6 and evaporated to yield purple

crystals. IR data (Nujol, cm'l): 3342 (m), 3291 (m), 2247 (w), 2147 (m),

133

2125 (m), 2093 (w), 1891 (s), 1764 (8, br), 1590 (s), 1134 (m), 1058 (m),
958 (m), 889 (w), 771 (w), 596 (w), 512 (w), 441 (m), 220 (m), 208 (m).

4. SINGLE CRYSTAL X-RAY STRUCTURAL STUDIES
Crystallographic data were collected on a 1K (SMART 1000) CCD for 35
and on a 2K (SMART 2000) CCD diffractometer for 30. Both are equipped
with monchromated Mo Koc (L, = 0.71069 A) radiation. The source is a Mo
sealed tube with a 3KW generator. The frames were integrated in the Bruker
SAINT software package8 and the data were corrected for absorption using
the SADABS program.9 The SIR9710 and SHELX-97n crystallographic
software packages were used. Crystal parameters and basic information
pertaining to data collection and structure refinement are summarized in
Tables 3.1-3.2.

(1) [TpNi(CH3CN)3](PF6) (30)-

Single crystals of 30 were grown from a concentrated acetonitrile solution of
the complex at low temperatures (~ -15 °C). A pale-purple crystal of
dimensions 0.24 x 0.12 x 0.065 mm3 was mounted on the tip of a glass fiber
with Dow Corning silicone grease and placed in a cold N2 stream. Least

squares refinement using well-centered reflections in the range 4.04° < 20 <

46.60° gave a cell corresponding to a rhomohedral/hexagonal crystal system.

A total of 7319 data (1101 unique) with F(000) = 3288 were collected at

134

Table 3.1. Crystallographic information for [TpNi(CH3CN)3](PF6) (30)

 

 

30
Formula C15H19F6PNiNgB
Formula weight 539.28
Temperature (K) 110(2)
Space group R-3c
a (A) 11.4050(16)
b (A) 11.4050(16)
c (A) 60.470( 12)
a (°) 90
B (°) 90
Y (°) 120
Volume (A3) 6811.8(19)
Z 12
I),alc (Mg m'3) 1.579
Absorption coefficient(mm") 0.996

Crystal size (mm) 0.236 x 0.122 x 0.065
Reflections collected 7319
Independent reflections 1101
Rim 0.1486
Final R indices R1 = 0.1196

wR2 = 0.3642

 

R, = 2[nl=,| - IF, ll] / 20:01. wR2 = {2mm} — F52 / Z[w(F02)2]}”2. GOF =
{2[w(F02 - Fc2)2] / (n - p)}"2 where n = total number of reflections and p =
total number of parameters.

135

Table 3.2. Crystallographic information for [FeTp2](BF4) (35).

 

 

35
Formula C13H20B3F4FeN12
Formula weight 568.74
Temperature (K) 173(2)
Space group P -1
a (A) 11.694(5)
b (A) 11.888(5)
c (A) 11.889(5)
0: (°) 115.825(5)
B (°) 116.478(5)
7 (°) 94.832(5)
Volume (A3) 1249.6(9)
Z 2
D... (Mg m’3) 1.512
Absorption coefficient(mm'l) 0.667
Crystal size (mm) 0.20 x 0.30 x 0.15
Reflections collected 10745
Independent reflections 4969
Rint 0.1349
Final R indices R1 = 0.0970

wR2 = 0.2574

 

R1 = Z[IIF.| - IF. II] / 21m. wR2 = {Z[w(F.2 — 13.2)2 / 2[w(F.2)2]}”2. GOF =
{2[W(F02 — F.2)2] / (n — p)}”2 where n = total number of reflections and p =

total number of parameters.

136

110(2) K using the (1)-20 scan technique to a maximum 20 value of 46.60°.
Systematic absences from the data led to the choice of R-3c as the space
group. The final full-matrix, least-squares refinement was based on data with
F.2 > 40(F02) and parameters to give R1 = 0.1196 (wR2 = 0.3642) and R... =
0.1486. The transmission factors were in the range 0.585 to 1.00. The
goodness-of-fit index was 1.723, and the highest peak in the final difference
map was 2.992 e'/A3 which is located near the phosphorus atom of a
disordered (PF6)' anion. The hydrogen atoms were placed in calculated
positions and treated as riding atoms. A thermal ellipsoid plot is presented in

Figure 3.2.

(2) [FeTp2](BF4) (35)-

Single crystals of 35 were grown by slow evaporation of the acetonitrile
mother liquor. A red crystal of dimensions 0.20 x 0.30 x 0.15 mm3 was
mounted on the tip of a glass fiber with Dow Corning silicone grease and

placed in a cold N2 stream. Least squares refinement using well-centered
reflections in the range 4.06° < 20 < 57.54° gave a cell corresponding to a
triclinic crystal system. A total of 10745 data (4969 unique) with F(000) =
578 were collected at 173(2) K using the 00-20 scan technique to a maximum

20 value of 57.54°. The space group is P-l. The final full-matrix, least-

137

squares refinement was based on data with F.2 > 46(F02) and parameters to
give R1 = 0.0970 (wR2 = 0.2574)and R... = 0.2574. The transmission factors
ranged from 0.0106 to 1.00. The goodness-of-fit index was 0.571, and the
highest peak in the final difference map was 0.970 e'/A3. The hydrogen
atoms were placed in calculated positions and treated as riding atoms. A
thermal ellipsoid plot is presented in Figure 3.3.

3. RESULTS AND DISCUSSION

A. Syntheses

Much of the research in this area with the Wis-pyrazolylborate (Tp) ligand
was fleshed out by Trofimenko who prepared numerous Msz complexes
with divalent metals in water.12 This facially coordinating tridentate ligand is
of great utility because it is anionic and therefore helps to reduce the cationic
charge on the metal complex. The ligand can be used in both aqueous and
non-aqueous media, which is convenient for our goal to prepare a molecular
cube in a solvent such as acetonitrile. The Tp ligand is a tridentate,
monoanionic ligand that has been used extensively in transition metal and
main group coordination chemistry.l3 It is similar to the Cp family of ligands
which has been used successfully by Rauchfuss to prepare molecular cubes.
Both Cp’ and Tp' donate 6 electrons, occupy three coordination sites, and are

monanionic. Complexes of the fac—[(L3)M(S)3]11+ type possess three labile

138

 

 

2
I. 015)
t .5
0(4)
0 g.)
'5‘ C(58)
C(4Al <
"I,
C(SA)

Figure 3.2. Thermal ellipsoid plot of cation [TpNi(CH3CN)3]+ in (30) at the
50 % probability level. The hydrogen atoms were omitted for the
sake of clarity. (Image is presented in color)

139

 

Figure 3.3. Thermal ellipsoid representation of the cation [Fesz]+ in (35) at
the 50 % probability level. The hydrogen atoms were omitted for
the sake of clarity. (Image is presented in color)

140

sites occupied by either solvent molecules or weakly coordinating anions.
Transition metal tricyanide complexes, fac-[(L3)M'(CN)3], were synthesized
with only iron(III) and cobalt(II) with the Iris-pyrazolylborate ligand.
Transition metal complexes, fac—[(L3)M(S)3]“+, were synthesized with a
variety of 3d metals and counterions. One can envisage that the reaction
between fac-[(L3)M(S)3]"+ and fac—[(L3)M'(CN)3] could yield a molecular
cube (Figure 3.1.). The molecular cube is of particular interest, but a reaction
of this type could yield a portion of a cube or any number of open polymeric
species that could also be of interest.

(1) Complexes of [TpM(CH3CN)3]X M = Fe“, Co" and Ni"; X'= (an),
(PF.)' and (CF3SO3)'.

The complexes, [TpM(CH3CN)3]+, were synthesized from their
solvated precursors [M(CH3CN)6]X2 and one equivalent of Nan as depicted
in Figure 3.4. This chemistry is difficult to control, as the possibility for
obtaining the bis-substituted complexes, Msz, is always an issue, since they
are quite stable once formed. One other synthetic issue is that the halide
abstraction reaction leads to a by-product NaX. This by-product is difficult
to remove, but it can be separated from the product of interest, namely
[TpM(CH3CN)3]+, by reducing the volume of the reaction solution and

chilling it to ~0 °C for up to a few days. Colorless crystals of the by-product

141

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salts are formed under these conditions and can be removed by filtration. In
the cases of the (BF4)' and (PF.)' salts, the [TpM(CH3CN)3]+ products
exhibit two CH3CN stretches in the IR spectrum, while the triflate
counterion typically gives rise to three stretches. All complexes exhibit at
least one v(B-H) stretching mode in the range of 2450 - 2550 cm]. The IR
spectral data are summarized in Table 3.3. The compounds,
[NiTp(CH3CN)3](PF6) (30) and [CoTp(CH3CN)3](PF6)'4 are the only
precursors of this type for which we were able to obtain single crystals and
fully characterized by X-ray methods.

The reaction of [Ni(CH3CN)6](BF4)2 with one equivalent of Nan was
performed on a large scale, and, after reducing the volume, pink crystals
formed. The crystals are Nisz, which poses a problem for synthesizing
[TpNi(CH3CN)3]+ on a large scale. Evidently, the NiTp2 complex is highly
favored under concentrated conditions. The reaction was refluxed in
acetonitrile overnight and, after reduction of the solvent, neither a pink
precipitate nor pink crystals formed. The pink color is indicative of the
NiTp2 product, whereas the pale purple color is a sign of the desired
[TpNi(CH3CN)3]+ complex.

(2) K[TpFe(CN)3].

The reaction of Na[TpFeCl3] and three equivalents of cyanide was

143

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performed in methanol, based on the fact that ligand redistribution occurs in
an acetonitrile medium to form the thermodynamically stable complex,
[Femsz]+ and the anion [FemCLJZIS Kim and co-workers15 managed to
crystallize [EtaN][TpFeCl3] from THF due to its low solubility in this
solvent. The [Fesz]+ complex is blood-red in color which is typical of low-
spin iron(III) complexes with nitrogen donor ligands. The [TpFeCl3]'
complex is high-spin and is lighter red/orange in color. In order to prepare
[TpFe(CN)3]', the KCN was added very slowly to avoid substitution of the
Tp' ligand for CN' ligands (both reactions are depicted in Figure 3.5-3.6). In
addition, the reaction was carried out under an inert atmosphere to prevent

"1 centers. IR data measured on the red solid revealed

reduction of the Fe
cyanide stretches as well as the v(B-H) stretch at 2490 cm]. This supports
the formulation of the product as the tricyanide complex [TpFe(CN)3]'. The
cation could be either K+ or Na+, since the starting material was
Na[TpFeCl3] but CN' was introduced as KCN. Another approach to
synthesizing the tricyanide species is to react Na[TpFeCl3] with 3
equivalents of AgX, X: (BF4)', (PF.)' and (CF3SO3)', in methanol and then
reacting the partially solvated complex and reacting that with 3 equivalents

of cyanide. This approach was not successful, however, since it invariably

led to the formation of the [Fesz]+ complex. The [FeTp2](BF4) (35) salt was

145

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isolated from this type of reaction.

(3) [Et4N]2[C0TP(CN)3]-

The tricyanide complex was formed by adding three equivalents of cyanide
to the [TpCo(CH3CN)3]+ complex. The problem with this reaction is that
[TpCo(CH3CN)3]'r is difficult to purify, and the by—product salts NaX (X =
(BF4)’, (CF3SO3)' and (PF.)') are often present. This is the reason why
satisfactory elemental analyses could not be obtained for the product.
Moreover, it is difficult to be precisely stoichiometric with the CN' addition;
excess CN' inevitably leads to the formation of Cosz and [Cou(CN)6]‘L
and/or other undesired cyanide complexes. The IR data for the product
[EtaN]2[TpCo(CN)3] consists of two cyanide stretches located at 2127 and
2112 cm'1 which is consistent with the D3 symmetry of the proposed
molecular structure. The v(B-H) stretches appear at 2511 and 2428 cm".

(4) Nisz.

The neutral NiTp2 complex is known in the literature, but the synthetic route
is slightly different from the one that led to the product in this work. In the
present case, the complex was formed by reacting two equivalents of Nan
with [Ni(CH3CN)6](BF4)2 in acetonitrile. The synthetic route previously
reported by Trifimenko was performed in water. The crystal structure was

reported by Bandoli16 and co-workers and is isostructural with its cobalt

148

analogue.17

(5) (983)C0(CH3CN)3](PF6)2-

The 1,4,7-thiacyclononane ligand is known to bind to a metal center as a
facially tridentate ligand. The cations [M(9S3)2]2+ (M = Co, Ni and Cu) salts
have been fully characterized as the (BE) salts.18 The solvated starting
material, [Co(CH3CN)6](PF6)2, was reacted with one equivalent of the 983
ligand with no evidence for precipitation. The color of the [Co(9S3)2](BF4)2
complex is purple, whereas the reaction of the one equivalent of 9S3 with
[Co(CH3CN)6](PF6)2 salt leads to an orange colored product. It is obvious
that the compound [Co(9S3)2]2+ is not forming under these conditions. The
9S3 ligand can be identified by the presence of several bands19 in the IR
spectrum at 1480 (s), 1410 (m), 1260 (w), 937 (m), and 881 (s) cm". There
are a few other peaks relevant to the 983 ligand, but they overlap with the
Nujol or (PF6)' modes. The IR data were measured both in air and in an inert
atmosphere. The v(CEN) stretches were present only in the IR data for the
anaerobic sample, which implies the CH3CN ligands are readily lost in favor
of water molecules. The three CH3CN stretches are present at 2324 (m),
2296 (m) and 2248 (w) em".

(6) (9S3)COClz and [Co(9S3)2]C12.

An acetonitrile solution of CoClz was treated with both one and two

149

equivalents of 983 under an inert atmosphere. The results were essentially
the same in both cases, namely a navy precipitate immediately formed. In
both cases, the chloride salts are not readily soluble in acetonitrile but are
soluble in water. The (9S3)CoC12 (33) complex exhibits stretches in the IR
for the 9S3 ligand at 1439 (s), 1410 (s), 1274 (w), 937 (m), 904 (s), 825 (s)
and 820 (m) cm‘]. Assuming the environment around the cobalt(II) metal
center is octahedral, either one site for this complex is open or else it is
occupied by solvent. The reaction carried out in acetonitrile led to a product
with two weak v(C.=_N) stretches at 2279 and 2244 cm". The [Co(9S3)2]C12
(34) complex exhibits stretches in the IR spectrum for the 983 ligand at 1455
(m), 1441 (m), 1405 (m), 1279 (m), 936 (m), 902 (s), 820 (s) cm". In both
cases, the IR data demonstrates the presence of the 983 ligand.

B. Reactivity Studies

(1) Reaction between [TpFe(CH3CN)3](CF3SO3)2 and K[TpFe(CN)3].
Equimolar solutions of [TpFe(CH3CN)3](CF3SO3)2 and K[TpFe(CN)3] were
reacted by addition of the solvated precursor into the cyanide complex. A
green precipitate formed almost immediately leaving behind a red solution.
The IR data for the green precipitate indicates that redistribution of the
ligands has occurred. The IR data consist of two peaks in the cyanide region

at 2090 (m) and 2066 (m) cm]. No v(B-H) stretch was observed. The

150

v(CEN) mode for K[TpFe(CN)3] is located at 2118 cm'l, therefore the
cyanide species in the product is either in a different environment or the
metal center is FeII instead of Fem. A v(B-H) stretch (2474 cm") appears in
IR data for the orange/red solution with no cyanide stretches being evident.
This implies that [Fesz]+ is being formed, because if neutral Fesz had
formed, it would have precipitated from solution due to its low solubility.
The green precipitate contains an iron(II) cyanide species as judged by the
fact that the cyanide stretches occur at lower energies than the corresponding

1" starting material.

modes for the original Fe
(2) Reaction between [EtaN]2[TpCo(CN)3] and (dien)Ni(NO3)2.
An excess of (dien)Ni(NO3)2 was combined with [EtaN]2[TpCo(CN)3] which

led to the production of a green precipitate and a colorless solution. The IR
spectrum of the green precipitate contains a strong v(CEN) mode at 2164
em], but no v(B-H) stretch was evident. The v(CEN) is shifted to higher
energy from the [EtaN]2[TpCo(CN)3] starting material at 2127 (m) and 2112
(m) cm], which is an indication that the nitrogen end of the cyanide ligand is
bound to another metal.

(3) Reaction of [Et4N]3[(CO)3Mo(CN)3] with [(9S3)Co(CH3CN)3](PF6)2.

An excess of [(9S3)Co(CH3CN)3](PF6)2 was added dropwise to an

151

acetonitrile solution of [EtaN]3[(CO)3Mo(CN)3] to yield a black precipitate.
The IR data of the black precipitate indicates the presence of cyanide,
carbonyl and 9S3 ligands. A polymer could have formed, since the black
precipitate formed immediately. The v(CEO) stretches are shifted to higher
energy from the parent complex to 1888 (3, br), 1792 (s, br) and 1635 (s, br)
cm"1 from 1850 (s), 1706 (s, br) cm'1 which is an indication of less 7t-
backbonding. The v(CEN) stretch in the parent complex is located at 2065
(s) cm", whereas the black precipitate exhibits two features at 2098 (8, br)
and 2027 (s) cm". The 983 modes appear at 1287 (s, br), 936 (m) and 902
(m) cm‘l. The v(CEN) modes of CH3CN in the cobalt starting material, have
shifted from 2324 (m), 2296 (m) and 2248 (w) em1 to 2310 (w), 2284 (w)
and 2248 (w) cm". Efforts to grow crystals of the black precipitate by slow
diffusion of the cobalt complex dissolved in methanol into a solution of the
molybdenum complex dissolved in acetonitrile led to the immediate
deposition of a black precipitate.

(4) Reaction of [EtaN]3[(CO)3Mo(CN)3] with (THF)3CrCl3 and

Na[TpCrCl3].

The complex [EtaN]3[(CO)3Mo(CN)3] was reacted with an excess of
(THF)3CrCl3 or Na[TpCrCl3] in acetonitrile. The solutions turn red with the

addition of the Cr(III) complexes and both red products exhibit similar IR

152

data. The (THF)3CrC13 starting material produced a red product with a single
cyanide stretch located at 2101 (s), and carbonyl stretches at 1995 (s), 1876
(s, br) and 1760 (s, br) cm'l. The product from the reaction of [TpCrCl3]+
complex exhibits similar cyanide and carbonyl stretches at 2096 (m), 2073
(m), 1996 (w), 1946 (w), 1883 (m) and 1782 (m, br) em}. No v(B-H)
stretches are present in the latter case indicating that the cyanide on the
molybdenum complex must have displaced the Tp' ligand. Since the red
product is soluble in acetonitrile, it is unlikely to be a polymer. The cyanide
stretches in both cases are shifted to higher energies indicating that the
nitrogen end of the cyanide ligand is bound to another metal atom. Efforts to
grow crystals by slow diffusion of diethyl ether/hexanes layer into an
acetonitrile solution containing the red product failed. The three carbonyls
should be good facially capping ligands in much the same manner as a Tp'
ligand, which would leave three orthogonal sites with cyanide for the
formation of a molecular cube.

(5) Reaction between [EtaN]3[(CO)3Mo(CN)3] and (dien)Ni(NO3)2.

A slight excess of (dien)Ni(NO3)2 was added dropwise to a solution of
[EtaN]3[(CO)3Mo(CN)3] to produce a yellow precipitate and a pale yellow
solution. The IR spectrum of the yellow precipitate indicates the presence of

both cyanide and carbonyl stretches. The cyanide stretches of

153

[EtaN]3[(CO)3Mo(CN)3] appear at 2065 (s) cm'1 while that of the precipitate
have shifted to higher energies, namely to 2147 (m) and 2125 (m) cm'l. The
carbonyl stretches for the precipitate appear at 1891 (s) and 1764 (3, br) cm'
‘, which are higher in energy than the molybdenum starting material (1850
(s) and 1706 (3, br) cm'l). A small amount of KPF. was added to the pale
yellow solution in an attempt to grow crystals of the yellow precipitate. The
pale yellow solution with the KPF6 was removed from the dry box and
evaporated with the vial cap slightly ajar to allow for slow evaporation. The
purple crystals that formed were analyzed by X-ray crystallography and
found to be [Ni(dien)2](NO3)2, which is a result of a rearrangement of the
starting material. The yellow precipitate, which is insoluble in most
common solvents, did not change color in air. Most likely, if the compound
contained Mo(0), it would readily oxidize, so it is likely that the Mo
oxidation state in this yellow precipitate is higher, and, since the compound
is insoluble, it may be a polymer. Efforts to grow crystals by layering
[EtaN]3[(CO)3Mo(CN)3] in acetonitrile with the [(dien)Ni(NO3)2] dissolved
in methanol in test tubes in the dry box yielded only yellow precipitate but
no crystals.

C. Molecular Structures

154

(l) [TpNi(CH3CN)3](PFo) (30)-

The [TpNi(CH3CN)3]+ cation possesses one Tp' ligand acting as a typical
facial tridentate ligand bound to Ni(l) through the nitrogen atoms. Three
acetonitrile molecules complete the octahedral environment around Ni(l).
The Ni and (PF.)' anions are located on special positions. The asymmetric
unit is composed of one third of the molecule. The Ni(1)-N(Tp) bond length
is 2.066(6) A while the Ni(l)-N(CH3CN) distance is 2.088(7) A. For
comparison, the Ni-N(Tp) bond distances in NiTp2 are in the range of
2.104(3) to 2.087(2) A. The Ni(l)-N(CH3CN) bond distances are longer than
the corresponding distances to the Tp, indicating that they are not
coordinated as tightly to the metal. The angle between the coordinated
acetonitrile molecules is 874°, whereas the angle between the pyrazole rings
is 88.1(2)°. The trans angle between a pyrazolylborate nitrogen atom and an
acetonitrile molecule is 166.3(6)°. The angle C(5)-C(4)—N(3), subtended by
the CH3CN ligand is nearly ideal at 177.8°. The C-N bonds within the
acetonitrile ligands are typical (e.g. 1.135(10) A). Selected bond distances
and angles are given in Table 3.4.

(2) [FeTp2](BF4) (35)-

The [FeTp2]+ cation in (35) possesses two Tp ligands that act as tridentate

facial ligands coordinated to Fe(l) through the nitrogen atoms. The Fe(1)-

155

N(Tp) bond lengths are in the range of 1.930(5) — 1.979(6) A and the Fe(2)-
N(Tp) distances are in the range of 1.933(5) — 1.966(6) A. The angles
between pyrazole rings around Fe(l) are in the range 88.6(2) — 91.4(2)°. The
angles between the pyrazole rings around Fe(2) are between 88.8(2) and
91.2(2)°. The asymmetric unit of this molecule is one-half of the two iron
atoms Fe(l) and Fe(2) and one [BF4]' anion. In the asymmetric unit, the
environment around Fe(l) consists of one complete Tp' ligand. The
environment around Fe(l) consists of four Fe(1)-N(Tp) bonds, two of each
at 1.930(5) and 1.939(5) A and two longer Fe(1)-N(Tp) bond lengths of
1.979(6) A. In contrast, the environment around Fe(2) has four longer Fe(2)-
N(Tp) bond lengths with two each at 1.966(5) and 1.960(5) A, and two
Fe(2)-N(Tp) bond distances that are slightly shorter at 1.933(5) A. Selected
bond distances and bond angles are listed in Table 3.5.

D. Magnetic Data

Magnetic susceptibility studies were conducted to establish the ground state
spin values for the new paramagnetic molecular building blocks. This
information is useful for predicting the number of unpaired electrons that
one might expect for a given molecular cube assembly reaction.20 Magnetic
moments at room temperature for molecular cube precursors are summarized

in Table 3.6.

156

Table 3.4. Selected bond distances [A] and angles [°]
for [TpNi(CH3CN)3](PF6) (30).

 

 

 

 

Bond Distances
A B A-B [A]

Ni( 1) N( 1) 2.066(6)

Ni( 1) N (3) 2.088(6)

C(3) N(3) 1.135(10)

Bond Angles

A B C A-B-C [°]
N(l) Ni(l) N(la) 88.1(2)
N( 1) Ni( 1) N (3) 94.0(2)
Ni(l) N(3) C(4) 166.3(6)
N(3) C(4) C(5) 177.8(8)

157

Table 3.5. Selected bond distances [A] and angles [°] for [FeTp2](BF4) (35).

 

 

 

 

Bond Distances

A B A-B [A]
Fe( 1) N( 1) 1.930(5)
Fe( 1) N(3) 1.939(5)
Fe( 1) N(5) 1.979(6)
Fe(2) N(9) 1 960(5)
Fe(2) N(l 1) 1.966(5)

Bond Angles

A B C A-B-C [°]
N( 1) Fe( 1) N(3) 89.5(2)
N(l) Fe(l) N(5) 91.3(2)
N(3) Fe( 1) N(5) 91 .4(2)
N(7) Fe(2) N(l l) 90.2(2)
N(9) Fe(2) N(l 1) 91 .2(2)
N(7) Fe(2) N(9) 89.6(2)

158

 

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The tzg‘seg2 electron configuration for a NilI center in [TpNi(CH3CN)3](BF4)
(28) leads to a lien = 2.7 B.M. and g = 2. The experimentally observed it.“
and g values deviate slightly from the predicted spin-only value of 2.83 B.M.
and g = 2, but are consistent with literature reports of other octahedral NiII
complexes.” The tzg5eg2 electron configuration for a C011 center in
[TpCo(CH3CN)3]X with X = (BF4)' (24), (CF3SOg)' (25) lead to a “err = 3.69
and 4.33 B.M. with a g = 2 respectively, which are typical values for the
CoII configuration.20
The low-spin tzgi’egl electron configuration for the CoII center in
[TpCo(CN)3]2' leads to a u.” = 1.68 B.M. and g = 1.9, in good agreement
with the predicted spin-only values of Hart = 1.73 B.M. and g = 2. The low-
spin tzgsego electron configuration for a FeIII center in [FeTp2](BF4) (35) leads
to “err = 1.86 B.M. with a g = 2.16 which are slightly higher than the
predicted spin-only values of 1.73 B.M. and g ~ 2.0. The observed values
deviate due to spin-orbit coupling.20
4. SUMMARY AND CONCLUSIONS

The reaction of Nan with the solvated precursors, [M(CH3CN)6]X2,
is a convenient non-aqueous route to the corner ‘building blocks”
[TpM(CH3CN)3]"+. It is difficult to avoid the formation of the Msz

complexes, as they are stable products once formed. A problem with these

160

types of reactions is that the by-product salt NaX is difficult to remove
completely. This excess salt poses a problem for the next step, namely
preparation of [TpM(CN)3]"' from [TpM(CH3CN)3]“+ because the
contaminated sample of the latter precludes the use of a stoichiometric
addition of CN'. The synthetic approach to K[TpFe(CN)3] is more
straightforward, since three equivalents of cyanide can be added directly to
the Na[TpFeCl3] complex, thereby leading to the formation of [TpFe(CN)3]'
and KC]. If the [TpM(CN)3]“' complexes can be obtained in sufficient
quantity, reactions of these anions with metal ions in water, the solvent of
choice used for the corresponding tacn chemistry of Long and co—workers, is

a promising avenue for future work.

161

5. REFERENCES

1. Dunbar, K. R.; Heintz, R. A. Prog. Inorg. Chem. 1997, 45, 283 and
references therein.

2. Klausmeyer, K. K.; Wilson, S. R.; Rauchfuss, T. B. J. Am. Chem. Soc.
1998, 121(12), 2705.

3. (a) Contakes, S. M.; Klausmeyer, K. K.; Milberg, R. M.; Wilson, S. R.;
Rauchfuss, T. B. Organometallics 1998, 17, 3633. (b) Contakes, S. M.;
Schmidt, M.; Rauchfuss, T. B. Chem. Commun. 1999, 1183. (c) Contakes, S.
M.; Klausmeyer, K. K.; Rauchfuss, T. B. Inorg. Chem. 2000, 39, 2069.

4. (a) Heinrich, J. L.; Berseth, P. A.; Long, J. R. Chem. Commun.
1998, 1231.

5. (a) Shores, M. P.; Beauvais, L. G.; Long, J. R. J Am. Chem. Soc 1999,
121, 775. (b) Shores, M. P.; Beauvais, L. G.; Long, J. R. Inorg. Chem. 1999,
38, 1648. (c) Bennett, M. V.; Shores, M. P.; Beauvais, L. G.; Long, J. R. J.
Am. Chem. Soc. 2000, 122, 6664.

6. Heintz, R. A.; Smith, J. A.; Szalay, P. S.; Weisgerber, A.; Dunbar, K. R.
submitted to Inorganic Syntheses.

7. Trofimenko, S. Inorganic Syntheses 1970, 12, 99.

8. SAINT 1000 and 6.0, Bruker Analytical X-ray Instruments, Madison, WI,

53719 (1999 and 2000)

162

9. Sheldrick, G. M. “SADABS, Siemens Area Detector Absorption
Correction”, Univ. of Gottingen, Gottingen, Germany (1998).

10. Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.; Giacovazza,
C.; Guagliardi, A.; Molitemi, A. G. G.; Polidori.G.; Spagna, R. J. Appl.
Crystallogr. 1999, 32, 115.

11. Sheldrick, G. M. SHELXTL version 5.10, Reference Manuel, Bruker
Industrial Automation, Analytical Instrument, Madison, WI 53719 (1999).
Program for Refinement of Crystal Structure, University of Gottingen,
Gottingen, Germany.

12. Trofimenko, S. J. Am. Chem. Soc. 1967, 89, 3170.

13. Trofimenko, S. Chem. Rev. 1993, 93, 943.

14. For details regarding [TpCo(CH3CN)3](PF6) please refer to the
Dissertation of P. S. Szalay Jr, Michigan State University August, 2001.

15. Cho, S.-H.; Whang, D.; Han, K.-N.; Kim, K. Inorg. Chem. 1992, 31,
519.

16. Bandoli, G.; Clemente, D. A.; Paolucci, G.; Doretti, L. Cryst. Struct.
Cbnun.1979,8,965.

17. Churchill, M. R.; Gold, K.; Maw, C. E. Inorg. Chem. 1970, 9, 1597.

18. Setzer, W. N.; Ogle, C. A.; Wilson, G. S.; Glass, R. S. Inorg. Chem.

1983, 22, 266.

163

19. (a) Hartman, J. A. R.; Hintsa, E. J.; Cooper, S. R. J. Am. Chem. Soc.
1986, 108, 1208. (b) Baker, P. K.; Drew, M. G. B.; Meehan, M. M. Inorg.
Chem, 1999, 2, 442.

20. (a) Carlin, R. L. Magnetochemistry, Springer-Verlag Berlin Heidelberg
1986. (b) Mabbs, F. E. Machin, D. J. Magnetism and Transition Metal

Complexes, London Chapman and Hall 1973.

164

Chapter IV
Cyanide Assemblies and Clusters

165

1. INTRODUCTION

Prussian blue, Fe4[Fe(CN)6]3ol4HzO, is an example of a 3-D cyanide
structure that exhibits ferromagnetic ordering at 5.5 K.‘ Analogues of
Prussian blue have been prepared with numerous other metals as illustrated
by the list provided in Table 1.1.2 These materials have also been the
inspiration for new architectures that involve the use of capping groups to
lower the dimensionality.3 For example, if hexacyanometallate anions are
reacted with metal centers capped with various bidentate, tridentate or
tetradentate ligands, new motifs can be formed. In this vein, Okfiwa and co-
workers reported early results in this field including l-D, 2-D and 3-D
architectures.4 One of the first reported examples is a ls-D rope-ladder motif,
[N i(en)2]3[F e(CN)6]202HzO, in which Ni atoms are coordinated to two
ethylenediamine (en) molecules in both the cis and trans arrangements. This
group has reported a series of compounds with this rope-ladder motif simply
by replacing the Fe111 center with Mnm, Crm or Com. The magnetic data reveal
no magnetic ordering with the Mnm, Cr‘Il or CoIII compounds but the F eIII
complex is metamagnetic.5 More recently the material
[Mn(en)]3[Cr(CN)6]204HzO was prepared which exhibits a 3-D structure

orders at 69 K; this is the highest ordering temperature among structurally

166

characterized molecular based magnets.6

In our laboratory, efforts are being made to synthesize motifs such as
molecular squares and cubes by using pre-designed precursors. The main
approach is to react the precursors cis-[(N-N)2M(S)2]n or fac-[(L3)M(S)3]“,
with hexacyanometallate anions to prepare discrete structures with interesting
magnetic properties.
2. EXPERIMENTAL
A. PHYSICAL METHODS
Infiared spectra were recorded on a Nicolet 42 spectrophotometer in the
Chemistry Department at Michigan State University or on a Nicolet 470 in
the Chemistry Department at Texas A&M University. Infrared spectra were
recorded at 4 cm’I resolution and 32 scans unless otherwise stated. Solid
samples were measured as Nujol mulls on KBr or CsI plates. Elemental
analyses were performed at Desert Analytics, Tucson, AZ or in the Chemistry
Department at Michigan State University; in the latter case a Perkin and
Elmer Series II CHNS/O analyzer 2400 was used. Magnetic measurements
were performed on a Quantum Design MPMS-5 instrument equipped with a
SQUID sensor housed in the Physics and Astronomy Department at Michigan
State University or a MPMS-XL SQUID magnetometer located in the

Chemistry Department at Texas A&M University. Scanning electron

167

micrographs (SEM) were obtained on a JEOL 6400 instrument at the Electron
Microscopy Center at Texas A & M University.

B. SYNTHESES

The starting materials K3 [Fe(CN)6] and K4[Fe(CN)6] were purchased from
Aldrich and used without further purification. Acetone and acetonitrile were
distilled over 3 A molecular sieves. Benzene, diethyl ether, THF and toluene
were distilled over sodium-potassium/benzophenone, whereas methylene
chloride was distilled over P205 under nitrogen atmosphere. Methanol and
ethanol were dried over magnesium alkoxide.

(1) Synthesis of {Mn(HzohMn(ZJ'-bpym)(H20)lz[F6(CN)612}«> (36)
Three equivalents of [(2,2'-bpym)2Mn(HzO)2](BF4)2 (0.049 g, 0.084 mmol) or
[(2,2'-bpyrn)2Mn(HzO)2](S04)7 in 25 mL of water were reacted with two
equivalents of K3[Fe(CN)6] (0.018 g, 0.056 mmol) in aqueous (25 mL)
solution to yield a brown precipitate and a yellow filtrate after 12 h. The
brown precipitate was collected by filtration and washed with water (2 x 10
mL) followed by acetone (2 x 10 mL). The filtrate was slowly evaporated to
give a brown crystalline material, which was washed with water to remove
soluble by-products. Combined yield: (0.020 g, 64%) IR data (Nujol, cm"):

2146 (s), 2119 (s), 2065 (w), 1609 (m), 1591 (w), 1572 (s), 1558 (s), 1407

168

(s), 1301 (w), 1267 (w), 1208 (w), 1146 (w), 1103 (m), 1010 (m), 960 (m),
825 (m), 761 (m), 689 (w), 657 (m), 526 (w), 419 (m), 226 (w).
(2) Syntheses 0‘ {1C0(2,2'-bpy)213[Fe(Cl‘Dolz}+ (37)

A. Reaction of (2,2'-bpy)2Co(CF3SO3)2 with [EtMflFdCNk]
Three equivalents of (2,2'-bpy)2Co(CF3SO3)2 (0.103 g, 0.154 mmol)
dissolved in 20 mL of water were reacted with two equivalents of
[Et4N]3[Fe(CN)6] (0.062 g, 0.103 mmol) dissolved in 25 mL of water. The
reaction was stirred overnight, after which time a blue precipitate was
obtained by filtration and washed with water (2 x 10 mL) followed by
acetone (2 x 10 mL). IR data for the blue precipitate (Nujol, cm"): 2137 (w),
2106 (m), 2096 (m), 2066 (s), 1635 (w, br), 1605 (m), 1567 (w), 1498 (m),
1325 (w), 1313 (m), 1276 (w), 1243 (m), 1162 (m), 1110 (w), 1074 (w),
1037 (w), 1027 (w), 966 (w, br), 936 (w), 917 (w), 890 (w), 844 (w), 801
(w), 770 (m), 737 (m), 671 (w), 651 (w), 589 (w), 545 (m), 503 (w), 467 (w),
440 (w), 424 (w), 415 (w), 374 (w), 351 (w).

B. Reaction of [Co(2,2'-bpy)3](ClO4)2 with K4[Fe(CN)5]
Three equivalents of [Co(2,2'-bpy)3](ClO4)2 (0.233 g, 0.321 mmol) dissolved
in 25 mL of water and K4[Fe(CN)6] (0.090 g, 0.213 mmol) in aqueous (25
mL) solution were added together and stirred overnight to yield a blue

precipitate. The navy blue precipitate was collected by filtration, washed with

169

water (2 x 10 mL) followed by acetone (2 x 10 mL). Yield: 95.4 mg IR data
of the blue precipitate (Nujol, cm"): 2138 (m), 2108 (m), 2094 (m), 2068 (s),
1639 (w, br), 1606 (m), 1567 (m), 1498 (m), 1314 (m), 1274 (w), 1243 (m),
1162 (m), 1110 (w), 1074 (m), 1033 (w), 1029 (w), 968 (w), 935 (w), 917
(w), 890 (w), 843 (w), 802 (w), 768 (m), 669 (w), 652 (w), 589 (w), 545 (m),
503 (w), 468 (w), 415 (w), 377 (w), 351 (w), 282 (w), 254 (w), 240 (w).

C. Reaction of (2,2'-bpy)2Co(CF3803)2 with K3[Fe(CN)‘]
A deoxygenated water solution (25 mL) of K3[Fe(CN)6] (0.085 g, 0.258
mmol) was treated with three equivalents of (2,2'-bpy)2Co(CF3SOg)2 (0.258 g,
0.386 mmol) in 25 mL of deoxygenated water. After stirring for 12 h, the
resulting navy blue precipitate was filtered under nitrogen, washed with water
(2 x 10 mL) followed by 10 mL of diethyl ether, and finally dried in air.
Yield: 206 mg. IR data of the navy blue precipitate. (Nujol, cm-l): 2141 (w),
2108 (m), 2094 (m), 2067 (s), 1653 (w), 1606 (m), 1605 (m), 1575 (w), 1569
(w), 1560 (w), 1558 (w), 1544 (w), 1365 (s), 1309 (m), 1274 (w), 1244 (w),
1169 (m), 1159 (m), 1108 (w), 1074 (m), 1037 (m), 1030 (m), 966 (m), 934
(w), 918 (w), 891 (w), 840 (w), 769 (m), 733 (m), 668 (w), 652 (w), 587 (w),
542 (m), 500 (w), 470 (w), 459 (w), 416 (w).

D. Reaction of (2,2'-bpy)zCo(CF3SO3)z with [K-l8-C-6]3[Fe(CN)5]

Three equivalents of (2,2'-bpy)2Co(CF3SO3)2 (0.200 g, 0.299 mmol)

170

dissolved in 25 mL of acetonitrile were reacted with two equivalents of [K-
18-C-6]3[Fe(CN)6] (0.224 g, 0.199 mmol) in acetonitrile (25 mL). The
reaction was stirred for 12 h, after which time a navy blue precipitate was
collected by filtration, washed with acetonitrile (2 x 10 mL) followed by
acetone (2 x 10 mL), and dried in air. The filtrate was colorless. Yield: 174.5
mg. IR data of the navy blue precipitate (Nujol, cm”): 2138 (w), 2106 (s),
2063 (s, br), 1639 (m), 1606 (s), 1567 (m), 1500 (m), 1314 (m), 1244 (m),
1162 (m), 1109 (m), 1074 (m), 1038 (m), 968 (w), 890 (w), 769 (s), 653 (w),
590 (w), 546 (m), 468 (w), 415 (w), 351 (w).

E. Reaction of (2,2'-bpy)2Co(CF3SO3)2 with [K-18-C-6]3[Fe(CN)6]

A sample of (2,2'-bpy)2Co(CF3SO3)2 (0.201 g, 0.300 mmol) dissolved in 25
mL of methanol was combined with two equivalents of [K-l 8-C-6]3[Fe(CN)6]
(0.225 g, 0.201 mmol) in 25 mL of methanol. After 12 h of stirring, the navy
blue precipitate that had formed was collected by filtration, washed with
methanol (2 x 10 mL) and diethyl ether (10 mL), and dried in air. The filtrate
was colorless. Yield: 142.7 mg. IR data of the navy blue precipitate (Nujol,
cm“): 2144 (w), 2105 (m), 2056 (s, br), 1636 (w, br), 1600 (s), 1566 (m),
1497 (w), 1359(8), 1325 (w), 1312 (m), 1271 (m), 1241 (s), 1222 (m), 1154
(s), 1106 (m), 1069 (m), 1028 (s), 972 (w), 921 (w), 894 (w), 844 (w), 801

(w), 765 (s), 733 (m), 668 (w), 637 (m), 584 (m), 543 (m), 463 (m), 412 (m).

171

F. Reaction of (2,2'-bpy)2Co(CF3SO3)2 with K3[Fe(CN)6]
Three equivalents of (2,2'-bpy)2Co(CF3SOg)2 (0.275 g, 0.411 mmol)
dissolved in 25 mL of water were treated with a water solution (25 mL) of
K3[Fe(CN)6] (0.090 g, 0.273 mmol) which led to the production of an
immediate navy blue precipitate. The solid was collected by filtration, washed
with water (2 x 10 mL) followed by 10 mL of diethyl ether, and dried in air.
Yield: 232 mg. IR data of the navy blue precipitate (Nujol, cm"): 2141 (w),
2106 (m), 2097 (m), 2066 (s), 1636 (w, br), 1606 (m), 1604 (m), 1574 (w),
1567 (w), 1365 (s), 1307 (m), 1273 (w), 1245 (w), 1171 (m), 1161 (m), 1110
(w), 1074 (m), 1032 (m), 968 (m), 938 (w), 921 (w), 891 (w), 845 (w), 801
(w), 769 (m), 737 (s), 648 (w), 588 (w), 545 (m), 463 (w), 412 (w).

G. Reaction of [Co(2,2'-bpy)3](ClOa)z with K3[Fe(CN)6]
A sample of [Co(2,2'-bpy)3](ClO4)2 (0.218 g, 0.300 mmol) dissolved in 25
mL of water was reacted with two equivalents of K3[Fe(CN)6] (0.067 g,
0.204 mmol) in 25 mL of water. The resulting navy blue solid was collected
by filtration, washed with water (2 x 10 mL) followed by 10 mL of diethyl
ether, and dried in air. Yield: 170.1 mg. IR data of the navy blue precipitate
(Nujol, cm"): 2139 (w), 2109 (m), 2094 (m), 2067 (s, br), 1650 (w, br), 1638
(w, br), 1606 (m), 1568 (w), 1500 (w), 1361 (s), 1332 (w), 1315 (m), 1276

(w), 1244 (m), 1163 (m), 1096 (m), 1076 (m), 1039 (m), 1018 (w), 969 (w),

172

890 (w), 839 (w), 801 (w), 767 (s), 733 (m), 670 (w), 652 (w), 625 (w), 588
(w), 545 (m), 501 (w), 464 (w), 415 (w).

H. Reaction of [Co(2,2'-bpy)3](C104)2 with [K-18-C-6]3[Fe(CN)5]
An aqueous (25 mL) solution of [Co(2,2'-bpy)3](ClO4)2 (0.219 g, 0.302
mmol) was reacted with [K-18-C-6]3[Fe(CN)6] (0.226 g, 0.201 mmol) in 25
mL of water. After 12 h, a navy blue precipitate was collected by filtration
and washed with water (2 x 10 mL) followed by 10 mL of diethyl ether and
finally dried in air. Yield: 148.6 mg. IR data of the navy blue precipitate
(Nujol, cm“): 2139 (w), 2109 (m), 2094 (m), 2067 (s, br), 1645 (w, br), 1606
(m), 1568 (w), 1500 (m), 1362(8), 1329 (w), 1315 (m), 1278 (w), 1244 (m),
1220 (w), 1175 (w), 1163 (m), 1110 (m), 1072 (m), 1039 (m), 1025 (w), 967
(w), 891 (w), 841 (w), 802 (w), 767 (s), 731 (m), 670 (w), 653 (w), 588 (w),
544 (m), 468 (w), 416 (w).

1. Reaction of (2,2'-bpy)zCo(CF3803)2 with K4[Fe(CN)6]
Three equivalents of (2,2'-bpy)2Co(CF3SO3)2 (0.253 g, 0.378 mmol) in 25 mL
of water were reacted with K4[Fe(CN)6] (0.107 g, 0.254 mmol) in 25 mL of
water. After 12 h of stirring, a navy blue precipitate was collected by filtration
and washed with water (2 x 10 mL) followed by 10 mL of diethyl ether and
dried in air. The intensely colored blue filtrate was slowly evaporated to yield

a navy blue solid, which was washed with water (1 x 10 mL) and diethyl

173

ether (10 mL) and dried in air. IR data on both batches of blue solids indicate
that the samples are the same product. Combined yield: 98.8 mg. IR data of
the navy blue precipitate (Nujol, cm“): 2140 (w), 2108 (m), 2094 (m), 2067
(s, br), 1639 (w, br), 1606(8), 1566 (w), 1499 (w), 1357 (s), 1331 (w), 1314
(m), 1278 (w), 1244 (m), 1178 (w), 1163 (m), 1131 (w), 1109 (m), 1073 (m),
1037 (m), 1030 (m), 968 (w), 891 (w), 845 (w), 801 (w), 769(8), 735 (m), 672
(w), 651 (w), 618 (w), 588 (m), 542 (m), 467 (w), 417 (w).

(3) Synthesis 01’ [Ni(ZJ'-bPY)2(0H2)l[Ni(ZJ'-bPY)2]2[Fe(CN)olz (38)

Three equivalents of [(2,2'—bpy)2Ni(OH2)2](CF3803); (0.159 g, 0.238 mmol)
in 25 mL of water were reacted with K3[Fe(CN)6] (0.052 g, 0.159 mmol) in
25 mL of water. An immediate yellow/brown precipitate formed. The reaction
was stirred for 12 h, after which time the precipitate was collected by
filtration and washed with (2 x 10 mL) of water followed by 10 m1. of
acetone and dried in air. The yellow filtrate was evaporated next to an oven,
and after a certain period of time, a yellow brown precipitate was present
admixed with dark orange/red/brown crystals. These crystals were identified
as [Ni(2,2'-bpy)2(OH2)][Ni(2,2'-bpy)2]2[Fe(CN)6]2 (38). Yield of
yellow/brown solid 68.7 mg. IR data of the initial yellow/brown precipitate
(Nujol, cm“): 2142 (m), 2113 (s), 1630 (w), 1604 (s), 1598 (s), 1575 (m),

1567 (m), 1313 (s), 1247 (w), 1170 (w), 1156 (m), 1103 (w), 1060 (w), 1043

174

(w), 1022 (m), 971 (w), 891 (w), 847 (w), 811 (w), 765 (s), 736 (s), 652 (m),
632 (m), 413 (m), 283 (w), 251 (w), 247 (w), 221 (w), 215 (w), 212 (w), 208
(w), 205 (w), 201 (w).

(4) Synthesis of [Zn(phen)3] [Zn(phen)2]2[Fe(CN)5]2 (39)

An aqueous solution (25 mL) of (phen)2Zn(NO3)2 (0.103 g, 0.187 mmol)7
reacts instantaneously with K3[Fe(CN)6] (0.041 g, 0.124 mmol) in 25 mL of
water to yield a yellow precipitate. After the reaction was stirred for 12 h, the
yellow precipitate was collected by filtration. The yellow precipitate was
washed with water (2 x 10 mL) followed by acetone (2 x 10 mL) and dried in
air. The resulting yellow filtrate slowly evaporated to produce orange crystals
of [Zn(phen)3][Zn(phen)2]2[Fe(CN)6]2. Yield: 96.2 mg. IR data for the yellow
precipitate (Nujol, cm"): 2150 (m), 2113 (m), 2062 (w), 1623 (m), 1579 (m),
1517 (m), 1425 (s), 1341 (w), 1305 (w), 1260 (w), 1224 (m), 1143 (m), 1103
(m), 966 (w), 867 (m), 850 (m), 774 (w), 640 (m), 421 (m), 288 (m), 241 (w),
225 (w), 208 (w). IR data of the orange crystals (Nujol, cm"): 2151 (m),
2143 (w), 2127 (w), 2108 (m), 1623 (m), 1578 (m), 1517 (m), 1142 (m),
1103 (m), 965 (w, br), 867 (m), 847 (s), 640 (m), 421 (m), 285 (w), 241 (w).
C. REACTIVITY STUDIES

(1) Reaction of (2,2'-bpy)2Mn(CF3803)2 with [K-l8-C-6]3[Fe(CN)5]

175

Three equivalents of (2,2'-bpy)2Mn(CF3SO3)2 (0.072 g, 0.108 mmol) in 20
mL of acetonitrile/20 mL of methanol were reacted with two equivalents of
[K-18-C-6]3[Fe(CN)6] (0.078 g, 0.076 mmol) in a mixture of acetonitrile and
methanol (20mL/20mL) After 1 hour, a brown precipitate was present in a
colorless filtrate. The brown precipitate was collected by filtration, washed
with methanol (2 x 10 mL) followed by acetone (2 x 10 mL), and dried in air.
Yield: 35.4 mg. IR data (Nujol, cm“): 2143 (s), 2119 (m), 2063 (m), 1622
(m), 1590 (m), 1517 (w), 1494 (w), 1424 (s), 1342 (w), 1302 (w), 1260 (m),
1222 (m), 1143 (m), 1102 (m), 1030 (m), 865 (m), 848 (s), 774 (w), 639 (m),
420 (m), 277 (w).

(2) Reaction of (2,2'-bpy)2Mn(CF3803)2 with K3[Fe(CN)5]

An aqueous solution (25 mL) of (2,2'—bpy)2Mn(CF3SO3)2 (0.076 g, 0.114
mmol) was mixed with K3[Fe(CN)6] (0.038 g, 0.115 mmol) in 25 mL of
water. After 1 h, a brown precipitate had formed which was collected by
filtration, washed with water (2 x 10 mL) and acetone (2 x 10 mL), and
finally dried in air. Yield: 38.4 mg. IR data of the brown precipitate (Nujol,
cm"): 3368 (8, br), 2155 (w), 2142 (s), 2133 (s), 2122 (s), 2112 (s), 2078
(w), 2061 (w), 2038 (w), 1631 (w), 1601 (s), 1595 (s), 1575 (m), 1566 (m),
1490 (m), 1439(8), 1315 (m), 1245 (m), 1220 (w), 1174 (m), 1156 (m), 1116

(w), 1100 (w), 1061 (m), 1043 (w), 1016(8), 977 (w), 965 (w), 902 (w), 890

176

(w), 814 (w), 767(8), 737 (s), 647 (m), 626 (m), 411 (m), 351 (w), 227 (m).
(3) Reaction of (2,2'-bpy)2Mn(CF3SO3)2 with K3[Fe(CN)6]

Three equivalents of (2,2'-bpy)2Mn(CF3SO3)2 (0.034 g, 0.052 mmol) in 15
mL of water were reacted with K3[Fe(CN)6] (0.011 g, 0.034 mmol) in 15 mL
of water. A brown precipitate was apparent after 1 h. After 12 h of stirring,
the brown precipitate was collected by filtration, washed with water (2 x 10
mL) and acetone (2 x 10 mL), and dried in air. Yield: 9.2 mg. IR (Nujol, cm'
1): 2156 (w), 2142 (m), 2132 (m), 2119 (m), 2114 (m), 2080 (w), 2061 (w),
2026 (w), 1627 (w), 1601 (m), 1595 (s), 1575 (m), 1563 (m), 1489 (m), 1439
(s), 1365 (m), 1342 (w), 1314 (m), 1245 (w), 1170 (w), 1156 (m), 1101 (w),
1061 (w), 1042 (w), 1015 (m), 966 (w), 890 (w), 766 (s), 737 (m), 647 (m),
626 (w), 411 (m), 236 (w), 226 (w), 218 (w), 212 (m), 202 (s).

(4) Reaction of [Mn(2,2'-bpy)3](CIO4)2 with K3[Fe(CN)6]

One equivalent of [Mn(2,2'-bpy)3](ClO4)2 (0.077 g, 0.106 mmol) in 40 mL of
water was reacted with K3[Fe(CN)6] (0.035 g, 0.106 mmol) in 40 mL of
water. After 12 h of stirring, the resulting brown precipitate was collected by
filtration and washed with water (2 x 10 mL) followed by (2 x 10 mL)
acetone and dried in air. Yield: 10.3 mg. IR (Nujol, cm"): 2136 (m), 2120 (s),
2057 (m), 1631 (w), 1594(8), 1575 (m), 1565 (m), 1485 (m), 1313 (m), 1246

(m), 1216 (w), 1174 (w), 1157 (m), 1100 (m), 1062 (w), 1040 (w), 1014 (m),

177

968 (w, br), 935 (w), 915 (w), 902 (w), 890 (w), 844 (w), 812 (w), 767 (s),
737 (m), 646 (m), 625 (m), 589 (w), 412 (m), 211 (w).

(5) Reaction of [Mn(2,2'-bpy)3](ClO4)z with [K-l8-C-6]3[Fe(CN)6]

The precursors [Mn(2,2'-bpy)3](ClO4)2 (0.160 g, 0.222 mmol) and [K-18-C-
6]3[Fe(CN)(,] (0.165 g, 0.161 mmol) were combined in a Schlenk flask under
a nitrogen atmosphere, treated with 100 mL of acetonitrile, and refluxed for
12 h. During this time, a brown precipitate had formed in a colorless solution.
The solution was removed via a cannula and the brown precipitate was
washed with acetonitrile (2 x 20 mL) and diethyl ether (20 mL). The
washings were removed each time via a cannula and the product was dried
under vacuum. Yield 13.9 mg. IR data (Nujol, cm"): 2146 (s), 2118 (m),
2064 (m), 1603 (m), 1597 (m), 1575 (m), 1316 (w), 1245 (w), 1177 (w),
1157 (m), 1062 (w), 1019 (m), 772 (m), 737 (m), 651 (m), 628 (w), 420 (m),
412 (m), 230 (w), 226 (w), 219 (w), 214 (w), 212 (w), 207 (m), 206 (m), 203
(m), 202 (m).

(6) Reaction of (phen)2Mn(CF3SO3)2 with K3[Fe(CN)5]

Three equivalents of (phen)2Mn(CF3SO3)2 (0.067 g, 0.093 mmol) in 40 mL of
water/ 10 mL of methanol were reacted with K3[Fe(CN)6] (0.021 g, 0.063
mmol) in 40 mL of water. After 1 h, a brown precipitate was observed to

have formed. The reaction was stirred for a total of 12 h with no further

178

changes being observed. The brown precipitate was collected by filtration
and washed with water (2 x 10 mL) followed by acetone (2 x 10 mL) and
dried in air. Yield: 13.9mg. IR data (Nujol, cm"): 2142 (w), 2113 (m), 2090
(w), 2053 (w, br), 1733 (w), 1622 (m), 1589 (m), 1574 (m), 1514 (m), 1338
(m), 1303 (m), 1260 (w), 1219 (w), 1167 (w), 1143 (m), 1100 (m), 1087 (w),
1076 (w), 1029 (w), 1014 (w), 968 (m), 936 (w), 916 (w), 891 (m), 864 (m),
848 (s), 804 (w), 772 (m), 728 (m), 637 (w), 418 (w), 392 (w, br), 277 (w),
237 (w), 224 (w), 208 (w).

(7) Reaction of (phen)2Mn(CF3SO3)2 with [K-18-C-6]3 [Fe(CN)5]

A water solution (25 mL) of (phen)2Mn(CF3SO3)2 (0.055 g, 0.077 mmol) was
reacted with [K-18-C-6]3[Fe(CN)6] (0.086 g, 0.084 mmol) in 25 mL of water.
After 1 h, a yellow/brown precipitate was present. After 12 h of stirring, the
yellow/brown precipitate was collected by filtration and washed with 2 x 10
mL aliquots of water followed with 2 x 10 mL portions of acetone and dried
in air. Yield: 14.4 mg. IR data (Nujol, cm“): 2142 (w), 2112 (m), 1622 (m),
1589 (m), 1573 (m), 1514 (m), 1422 (m), 1338 (m), 1302 (w), 1260 (w),
1221 (w), 1169 (w), 1142 (m), 1101 (m), 1022 (w, br), 970 (w), 892 (w), 864
(m), 848 (m), 804 (w), 773 (m), 727 (s), 637 (m), 513 (w, br), 438 (w), 418
(m), 393 (w), 278 (w), 219 (w), 208 (m).

(8) Reaction of (phen)2Mn(CF3SO3)z with [K-l8-C-6]3[Fe(CN)5]

179

The compound (phen)2Mn(CF3SOg)2 (0.053 g, 0.075 mmol) was dissolved in
a mixture of acetonitrile and methanol (15 mL/lO mL) and reacted with [K-
18-C-6]3[Fe(CN)6] (0.056 g, 0.055 mmol) in 15 mL of acetonitrile/ 10 mL of
methanol. After one hour, a brown precipitate was present which was
collected by filtration after 12 h of continuous stirring. The precipitate was
washed with 10 mL of acetonitrile, 10 mL of methanol and 2 x 10 mL of
acetone, and finally dried aerobically. Yield: 15.2 mg. IR (Nujol, cm“): 2143
(w), 2114 (m), 2067 (w, br), 1622 (m), 1602 (w), 1590 (m), 1572 (m), 1515
(m), 1422 (m), 1340 (w), 1302 (w), 1254 (w), 1222 (w), 1168 (w), 1143 (m),
1101 (m), 1087 (m), 1050 (w), 1030 (w), 1016 (w), 970 (w), 934 (w), 916
(w), 892 (w), 864 (m), 848 (m), 806 (w), 773 (m), 728 (m), 637 (m), 589 (w),
554 (w), 510 (w), 436 (w), 418 (m), 395 (w), 277 (w), 238 (w), 219 (w), 212
(w), 206 (w).

(9) Reaction of [Co(2,2'-bpym)3](BF4)2 with [K-lS-C-6]3[Fe(CN)5]

Three equivalents of [Co(2,2'-bpym)3](BF4)2 (0.058 g, 0.083 mmol) and two
equivalents of [K-l8-C-6]3[Fe(CN)6] (0.064 g, 0.055 mmol) were placed in a
Schlenk flask, treated with 35 mL of acetonitrile, and refluxed for 3 days. No
reaction was apparent until a few drops of water were added, after which time
the solution turned purple and a purple precipitate appeared. The reaction was

stirred for 12 h, after which time the colorless solution was removed via a

180

cannula. The purple precipitate was washed with 2 x 20 mL aliquots of
acetonitrile and the washings were removed via a cannula. The solid was then
washed with 20 mL of diethyl ether, the washings were removed via a
cannula and discarded, and the solid was dried under vacuum. Yield: 12.8
mg. IR (Nujol, cm"): 2141 (w), 2119 (m), 2068 (s), 1638 (w, br), 1594 (w),
1576 (s), 1560 (m), 1408 (s), 1365 (m), 1352 (w), 1340 (w), 1305 (w), 1220
(w), 1168 (w), 1146 (w), 1105 (w), 1072 (w), 1026 (w), 1013 (w), 962 (w),
935 (w), 917 (w), 891 (w), 840 (w), 822 (w), 762 (m), 754 (w), 748 (w), 691
(w), 675 (w), 658 (w), 587 (w), 555 (w), 411 (w, br), 229 (w), 223 (w), 212
(m), 208 (w), 204 (m), 202 (m).

(10) Reaction of [Co(2,2'-bpym)3](BF4)z with K3[Fe(CN)6]

Three equivalents of [Co(2,2'-bpym)3](BF4)2 (0.049 g, 0.070 mmol) in 15 mL
of deoxygenated water were reacted with K3[Fe(CN)6] (0.015 g, 0.048 mmol)
in 15 mL of deoxygenated water. The solution turned purple in color, and
after 12 h, a gelatinous purple product was collected by filtration. The finely
divided solid was washed with water (2 x 5 mL) followed by acetone (2 x 10
mL) and dried in air. Yield: 12.1 mg. IR data of the purple product (Nujol,
cm"): 2117 (s), 2074 (8, br), 1629 (111, br), 1580 (s), 1575 (s), 1557 (s), 1407
(s), 1218 (m), 1029 (8, br), 822 (m), 760 (m), 747 (m), 689 (w), 675 (m), 659

(w), 541 (m), 466 (w), 212 (w).

181

(11) Reaction of (phen)2Co(NO3)2 with K3[Fe(CN)6]

Three equivalents of (phen)2Co(NO3)2 (0.090 g, 0.166 mmol) in 10 mL of
deoxygenated water were combined with K3[Fe(CN)6] (0.036 g, 0.111 mmol)

in 15 mL of deoxygenated water. A green precipitate formed instantaneously,

but the reaction was stirred for a total of 12 h to ensure that complete reaction

had occurred. The green precipitate was collected by filtration, washed with

water (2 x 10 mL) followed by acetone (2 x 10 mL), and dried in air. The

filtrate was pale green colored and upon evaporation yielded no suitable

crystals. Yield: 20.4 mg. IR (Nujol, cm"): 2144 (w), 2108 (s), 2074 (s), 1656

(m), 1629 (m, br), 1605 (m), 1584 (m), 1521 (m), 1494 (m), 1429 (s), 1413

(m), 1366 (s), 1347 (m), 1313 (m), 1262 (w), 1228 (m), 1207 (w), 1166 (w),
1153 (w), 1146 (m), 1111 (w), 1099 (w), 1039 (w), 1035 (w), 965 (w, br),
923 (w), 890 (w), 881 (w), 850 (s), 846 (s), 800 (w), 773 (w), 750 (m), 717
(s), 655 (w), 590 (w, br), 551 (w), 523 (w), 510 (w), 498 (w), 494 (w), 465
(w), 443 (w, sh), 393 (w, br), 246 (w), 239 (w), 228 (w), 222 (w), 218 (w),
214 (m), 211 (m), 209 (w), 207 (m), 205 (m), 200 (m).

(12) Reaction of (phen)2Co(NO3)z with K3|Fe(CN)6]

Three equivalents of (phen)2Co(NO3)2 (0.024 g, 0.046 mmol) in 10 mL of
water were combined with K3[Fe(CN)(,] (0.060 g, 0.184 mmol) in 15 mL of

water to yield an instantaneous green precipitate. The reaction was stirred for

182

12 h, and the green precipitate was collected by filtration, washed with water
(2 x 10 mL) followed by acetone (2 x 10 mL), and dried in air. The light blue
filtrate was allowed to slowly evaporate which led to the formation of very
thin light blue needles. Yield: 15.3 mg. IR (Nujol, cm"): 2108 (m), 2078 (m,
br), 1632 (w, br), 1604 (m), 1584 (m), 1521 (m), 1491 (w), 1427 (m), 1412
(m), 1363 (m), 1345 (m), 1313 (m), 1227 (m), 1168 (w), 1154 (m), 1143 (m),
1110 (w), 1099 (w), 1040 (w), 1035 (w), 971 (w), 921 (w), 881 (w), 842 (m),
800 (w), 773 (w), 749 (m), 717 (s), 654 (w), 590 (w), 522 (w), 441 (w), 394
(w, br), 226 (w), 221 (w), 219 (w), 216 (w), 211 (m, br), 208 (m), 205 (m),
203 (m).

(13) Reaction of [T pCo(CH3CN)3](PF6) with [K-18-C-6]3[Fe(CN)d

A sample of [TpCo(CH3CN)3](PF6) (0.073 g, 0.135 mmol) in 25 mL of
acetonitrile was combined with [K-18-C-6]3[Fe(CN)5] (0.151 g, 0.135 mmol)
in 25 mL of acetonitrile to give a blue/green solution. The solution was
reduced in volume to ~10 mL, after which time 40 mL of diethyl ether was
added to induce precipitation of a blue/green product. The colorless solution
was removed via a cannula and the blue/green product was dried under
vacuum. Yield: 0.543 mg. IR (Nujol, cm“): 3370 (s, br), 2109 (s), 2064 (s,
br), 1639 (m), 1501 (w), 1408 (m), 1350 (s), 1324 (w), 1286 (m), 1248 (m),

1217 (w), 1107 (s, br), 1047 (m), 963 (s), 837 (s), 771 (w), 660 (w), 620 (w),

183

557 (m), 528 (w), 406 (w, br), 243 (w, br).

(14) Reaction of (dien)Ni(NO3)2 with [K-l8-C-6]3[Fe(CN)6]

A sample of (dien)Ni(NO3)2 (0.044 g, 0.154 mmol) in 25 mL of
CH3OI-I/CH3CN was reacted with [K-18-C-6]3[Fe(CN)6] (0.176 g, 0.157
mmol) in a mixture of CH3OH/CH3CN (25 mL v/v). A dark orange/brown
solution resulted after 12 h of stirring. The volume of the solution was
reduced to ~10 mL, and 40 mL of diethyl ether was added to precipitate a
dark orange product. The colorless solution was decanted through a cannula,
and the product dried under vacuum. IR data (Nujol, cm"): 3341 (w), 3281
(w), 3172 (w), 2405 (w), 2361 (w), 2244 (w), 2149 (m), 2101 (s), 1974 (w),
1748 (w), 1740 (w), 1601 (m), 1284 (s), 1248 (s), 1103 (s), 963 (s), 837 (s),
591 (w), 531 (m), 389 (m), 253 (m).

(15) Reaction of (2,2'-bpy)2Ni(CF3803)1 with [K-18-C-6]3[Fe(CN)5]

Three equivalents of (2,2'-bpy)2 Ni(CF3SO3)2 (0.183 g, 0.273 mmol) and two
equivalents of [K-18-C-6]3[Fe(CN)6] (0.205 g, 0.183 mmol) were combined
in a Schlenk flask with 50 mL of acetonitrile and refluxed overnight to give a
yellow/brown precipitate in a colorless solution. The solution was removed
via a cannula, and the product washed with 40 mL of diethyl ether which was
removed by cannula and discarded. The yellow/brown product was dried

under vacuum. Yield 54.2 mg. IR data (Nujol, cm"): 3391 (m), 2156 (m),

184

2144 (m), 2112 (m), 2107 (m), 1638 (w), 1599 (s), 1576 (m), 1567 (m), 1492
(m), 1314 (m), 1249 (m), 1224 (w), 1157 (m), 1104 (m), 1062 (w), 1044 (w),
1023 (m), 961 (w), 765 (s), 736 (s), 652 (m), 639 (m), 518 (w), 413 (m).

(16) Reaction of [(2,2'-bpy)2Ni(CH3CN)2](PF6)2 with K3[Fe(CN)6]

Three equivalents of [(2,2'-bpy)2Ni(CH3CN)2](PF6)2 (0.320 g, 0.430 mmol) in
40 mL acetonitrile were added to a 10 mL acetonitrile/50 mL water solution
of K3[Fe(CN)6] (0.046 g, 0.139 mmol). An immediate brown precipitate
formed in an orange/yellow solution. The solution was removed through a
cannula, the brown precipitate was washed with 40 mL of diethyl ether, and
dried under vacuum. IR data (Nujol, cm"): 2148 (s), 2126 (m), 2087 (m),
1601 (s), 1568 (m), 1313 (m), 1155 (m), 1060 (w), 1026 (m), 844 (m), 765
(s), 736 (s), 653 (m), 582 (w), 554 (w), 411 (m, br).

(17) Reaction of (phen)2Zn(NO:,)2 with K3[Fe(CN)6]

Three equivalents of (phen)ZZn(NO3)2 (0.104 g, 0.189 mmol)8 in 50 mL of
water were reacted with K3[Fe(CN)6] (0.042 g, 0.127 mmol) in 50 mL of
water. A yellow precipitate immediately formed which was collected by
filtration, washed with water (2 x 10 mL) followed by acetone (2 x 10 mL),
and. dried in air. The yellow filtrate was slowly evaporated which led to the
deposition of a minor quantity of a yellow/orange crystalline material. Yield:

92.7 mg. IR (Nujol, cm"): 2151 (m), 2114 (m), 2062 (w), 1623 (m), 1585

185

(m), 1578 (m), 1518 (m), 1425 (s), 1340 (w), 1307 (w), 1223 (m), 1144 (m),
1104 (m), 967 (w), 867 (m), 851 (m), 775 (w), 641 (m), 421 (m), 287 (m),
236 (w), 230 (w), 223 (w), 213 (m), 210 (m), 208 (m), 206 (m), 204 (m), 203
(m), 201 (w).

(18) Reaction of (phenth(NO3)2 with K3[Fe(CN)6]

Three equivalents of (phen)2Zn(NO3)2 (0.102 g, 0.185 mmol) in 25 mL of
methanol were reacted with K3[Fe(CN)6] (0.041 g, 0.124 mmol) in 25 mL of
methanol. An orange/yellow precipitate formed within 12 h of stirring. The
precipitate was collected by filtration, washed with methanol (2 x 10 mL)
followed by acetone (2 x 10 mL), and dried in air. The orange filtrate was
slowly evaporated which yielded orange crystals of K3[Fe(CN)6]. Yield: 67.2
mg. IR (Nujol, cm"): 2147 (m), 2114 (m), 2077 (m), 1626 (m), 1577 (m),
1517 (m), 1342 (w), 1306 (w), 1224 (w), 1145 (m), 1102 (m), 866 (m), 850
(m), 773 (w), 641 (m), 421 (m), 226 (w), 222 (w), 221 (w), 217 (w), 216 (w),
214 (w), 211 (m), 209 (w), 208 (w), 206 (w), 202 (m).

(19) Reaction of (phen)2Zn(NO3)2 with K3[Fe(CN)6]

A sample of (phenth(NO3)2 (0.134 g, 0.244 mmol) in 25 mL of water was
reacted with an aqueous solution (25 mL) of K3[Fe(CN)6] (0.020 g, 0.060
mmol). A yellow precipitate formed immediately which was collected by

filtration, washed with water (2 x 10 mL) followed by acetone (2 x 10 mL),

186

and dried in air. The colorless filtrate was discarded. Yield: 51.5 mg. IR
(Nujol, cm"): 2150 (w), 2143 (w), 2114 (m), 2082 (w, br), 1623 (m), 1579
(w), 1518 (m), 1426 (m), 1305 (w), 1224 (w), 1144 (m), 1103 (m), 966 (w),
867 (m), 851 (m), 641 (w), 420 (w), 221 (w), 212 (w), 210 (w), 208 (m), 205
(m), 201 (m).

(20) Reaction of (phen)2Zn(NO3)2 with K3[Fe(CN)6]

An aqueous solution (25 mL) of (phen)ZZn(NO3)2 (0.130 g, 0.236 mmol) was
reacted with K3[Fe(CN)6] (0.078 g, 0.237 mmol) in 25 mL of water. An
immediate yellow precipitate formed, which was collected by filtration,
washed with water (2 x 10 mL) followed by acetone (2 x 10 mL), and dried in
air. The yellow filtrate was slowly evaporated in air to yield a mixture of
colorless and very small orange/yellow crystals. Yield of yellow solid: 132.2
mg. IR (Nujol, cm"): 2150 (w), 2143 (w), 2127 (w), 2112 (m), 1623 (m),
1579 (w), 1517 (m), 1425 (m), 1306 (w), 1224 (w), 1143 (m), 1103 (m), 966
(w, br), 867 (m), 851 (m), 641 (w), 421 (w), 288 (w), 240 (w), 225 (w), 221
(w), 215 (w), 211 (m), 208 (m), 201 (m).

(21) Reaction of (phen)2Zn(N03)2 with K4[Fe(CN)6]

Three equivalents of (phen)ZZn(NOg)2 (0.118 g, 0.214 mmol) in 25 mL of
water were combined with K4[Fe(CN)6] (0.031 g, 0.073 mmol) in 25 mL of

water. The immediate formation of a fluffy yellow/orange material occurred.

187

The orange/yellow product was isolated by filtration, washed with water (2 x
5 mL) followed by 10 mL of acetone, and dried in air. The colorless filtrate
was discarded. Yield: 55.5 mg. IR data (Nujol, cm"): 2056 (s), 1623 (m),
1579 (m), 1517 (m), 1427 (s), 1343 (w), 1306 (w), 1224 (w), 1143 (m), 1103
(m), 867 (m), 849 (s), 772 (w), 640 (w), 589 (m), 422 (w), 290 (w), 220 (w),
219 (w), 215 (w), 212 (w), 209 (w), 207 (w), 204 (w), 201 (w).

(22) Reaction of (phen)2Zn(N03)¢ with K4[Fe(CN)6]

Three equivalents of (phen)2Zn(NO3)2 (0.204 g, 0.371 mmol) in 25 mL of
water were reacted with K4[Fe(CN)6] (0.106 g, 0.251 mmol) in 25 mL of
water. A pale yellow/white fluffy solid formed, which was collected by
filtration, washed with water (2 x 5 mL) followed by 10 mL of acetone, and
dried ill air. The orange filtrate was evaporated, but no crystals were
obtained. Yield: 76.4 mg. IR data (Nujol, cm"): 2074 (s, br), 1622 (m), 1223
(m), 1142 (m), 1103 (m), 868 (m), 849 (s), 771 (m), 593 (s), 423 (m), 292
(m), 216 (w), 207 (w).

(23) Reaction of (phenthClz with K3 [Fe(CN)6]

Three equivalents of (pheannClz (0.104 g, 0.209 mmol) in 25 mL of water
were added to K3[Fe(CN)6] (0.046 g, 0.139 mmol) in 25 mL of water. The
resulting yellow precipitate was collected by filtration, washed with water (2

x 5 mL) followed by 10 mL of acetone, and dried in air. The colorless filtrate

188

was discarded. Yield: 121.5 mg. IR (Nujol, cm"): 3375 (m, br), 2151 (w),
2144 (w), 2126 (w), 2114 (m), 1624 (m), 1579 (w), 1518 (m), 1425 (m),
1224 (w), 1144 (m), 1104 (m), 967 (w), 867 (m), 851 (m), 641 (w), 421 (w),
225 (w), 219 (w) 216 (w), 212 (m), 210 (m), 207 (w), 204 (m), 202 (m).

(24) Reaction of (phenthClz with K3[Fe(CN)5]

Three equivalents of (phen)2ZnC12 (0.101 g, 0.203 mmol) in 50 mL of water
were reacted with K3[Fe(CN)6] (0.045 g, 0.136 mmol) in 50 mL of water. A
yellow precipitate formed which was separated fiom a colorless filtrate,
washed with water (2 x 5 mL) followed by 10 mL of acetone, and finally
dried in air. The colorless filtrate was discarded. Yield: 121.6 mg. IR (Nujol,
cm"): 3375 (m, br), 2151 (m), 2143 (m), 2127 (m), 2114 (s), 2088 (m), 1623
(m), 1579 (m), 1518 (s), 1495 (w), 1425 (w), 1340 (m), 1306 (w), 1224 (m),
1144 (m), 1104 (m), 967 (w), 889 (w), 867 (m), 851 (s), 773 (w), 641 (m),
421 (m), 288 (m), 241 (w), 232 (w), 227 (w), 219 (m), 215 (m), 212 (w), 211
(w), 209 (m), 208 (m), 207 (m), 204 (m), 203 (m), 201 (m).

(25) Reaction of [Zn(phen)3]Clz with K3[Fe(CN)5]

An aqueous sample (25 mL) of [Zn(phen)3]C12 (0.108 g, 0.159 mmol) was
reacted with K3[Fe(CN)6] (0.034 g, 0.103 mmol) in 25 mL of water. An
immediate yellow gel-like material formed, which was collected by filtration,

washed with (2 x 5 mL) of water followed by 10 mL of acetone, and dried in

189

air. The colorless filtrate was discarded. Yield: 59.3 mg. IR data (Nujol, cm'
I): 3292 (m, br), 2174 (s), 2165 (s), 2133 (w), 2097 (m), 2084 (m), 1623 (w),
1586 (m), 1579 (m), 1519 (m), 1494 (w), 1426 (s), 1225 (w), 1145 (m), 1104
(m), 867 (m), 850 (s), 771 (m), 643 (w), 446 (m, br), 423 (w), 293 (w), 243
(w), 238 (w), 225 (w), 220 (w), 214 (w), 211 (w), 208 (w), 206 (m), 205 (m),
201 (m).

(26) Reaction of [Zn(phen)3]Clz with K3[Fe(CN)6]

Three equivalents of [Zn(phen)3]C12 (0.103 g, 0.152 mmol) in 50 mL of water
were reacted with K3[Fe(CN)6] (0.032 g, 0.097 mmol) in 50 mL of water. A
gelatinous yellow product formed which was collected by filtration, washed
with water (2 x 5 mL) followed by 10 mL of acetone and dried in air. The
colorless filtrate was discarded. Yield: 55.8 mg. IR data (Nujol, cm"): 2173
(m), 2165 (m), 2133 (w), 2096 (m), 2082 (m), 1622 (w), 1585 (w), 1577 (w),
1515 (m), 1306 (w), 1225 (w), 1147 (m), 1101 (m), 868 (m), 850 (m), 773
(w), 642 (w), 446 (w, br), 294 (m), 242 (w), 237 (w), 232 (w), 228 (w), 220
(w), 216 (w), 212 (m), 209 (m), 205 (m), 201 (m).

(27) Reaction of (2,2'-bpy)2Zn(N03)z with K3 [Fe(CN)5]

An aqueous solution (25 mL) of (2,2'-bpy)ZZn(NO3)2 (0.157 g, 0.313 mmol)
was reacted with K3[Fe(CN)5] (0.069 g, 0.210 mmol) in 25 mL of water. An

immediate yellow precipitate formed which was collected by filtration,

190

 

washed with water (2 x 10 mL) followed by acetone (2 x 10 mL), and dried in
air. The nearly colorless filtrate was discarded. Yield: 116.2 mg. IR data
(Nujol, cm"): 2177 (s), 2168 (s), 2162 (s), 2124 (m), 2114 (m), 2108 (m),
2085 (s), 1607 (m), 1597 (s), 1577 (m), 1567 (m), 1492 (m), 1314 (m), 1249
(m), 1171 (m), 1156 (m), 1104 (w), 1062 (m), 1025 (m), 1013 (w), 966 (w),
890 (w), 844 (w), 767 (s), 734 (s), 652 (m), 630 (w), 597 (w), 526 (w), 447
(m), 414 (m), 239 (w), 211 (w), 209 (w).

(28) Reaction of (2,2'-bpy)2Zn(NO3)z with K4[Fe(CN)6]

Three equivalents of (2,2'-bpy)ZZn(NO3)2 (0.123 g, 0.246 mmol) in 25 mL of
water were reacted with K4[Fe(CN)6] (0.070 g, 0.166 mmol) in 25 mL of
water. As the reaction proceeded, the solution became cloudy and gel-like in
consistency and a yellow precipitate began to settle out. The yellow product
was collected by filtration, washed with water (2 x 5 mL) followed by 10 mL
of acetone, and dried in air. The filtrate was discarded. Yield: 86.5 mg. IR
data (Nujol, cm"): 2085 (s), 2062 (w), 2048 (w), 2034 (s), 1623 (m), 1580
(m), 1517 (m), 1496 (w), 1425 (s), 1344 (w), 1306 (w), 1224 (m), 1142 (m),
1103 (m), 867 (m), 849 (s), 773 (w), 641 (w), 586 (m), 421 (w), 285 (w), 216
(w), 205 (w).

(29) Reaction of (2,2'-bpy)22nClz with K3[Fe(CN)6]

A deoxygenated water solution (10 mL) of (2,2'-bpy)ZZnC12 (0.075 g, 0.167

191

 

 

mmol) was reacted with K3[Fe(CN)(,] (0.036 g, 0.109 mmol) in 15 mL of air-
free water. After stirring for 12 h, the yellow precipitate was collected by
filtration, washed with water (2 x 10 mL) followed by acetone (2 x 10 mL),
and dried in air. The pale yellow filtrate was slowly evaporated in air but did
not yield crystals. Yield: 42.2 mg. IR data (Nujol, cm“): 2162 (m), 2090 (s),
1607 (m), 1598 (m), 1578 (w), 1568 (w), 1492 (w), 1316 (m), 1249 (w),
1157 (m), 1061 (w), 1023 (m), 767 (m), 735 (m), 652 (m), 596 (m), 498 (w),
422 (w, br), 414 (m), 216 (w), 212 (w), 209 (w), 206 (m), 204 (w), 201 (w).
(30) Reaction of (2,2'-bpy)2ZnClz with K4[Fe(CN)5]

Three equivalents of (2,2'-bpy)2ZnC12 (0.084 g, 0.188 mmol) in 10 mL of
water were added to K4[Fe(CN)6] (0.054 g, 0.128 mmol) in 15 mL of water.
The solution became cloudy and a pale yellow/white gelatinous material was
collected by filtration, washed with water (2 x 5 mL) followed by 10 mL of
acetone, and dried in air. The filtrate was discarded. Yield: 54.6 mg. IR data
(Nujol, cm"): 2160 (w), 2097 (s), 2086 (s), 2061 (s), 1605 (m), 1596 (s),
1576 (m), 1314 (m), 1250 (m), 1173 (m), 1156 (m), 1102 (w), 1060 (m),
1023 (m), 974 (w), 764 (s), 734 (s), 651 (m), 628 (w), 592 (s), 494 (m), 413
(m), 235 (w), 221 (w), 216 (w), 212 (w), 211 (w), 206 (m), 203 (w).

C. SINGLE CRYSTAL X-RAY STRUCTURAL STUDIES

Crystallographic data for compounds 36, 37, 38, 39 and 40 were collected on

192

a 2K (SMART 2000) CCD diffractometer equipped with monchromated Mo
K010... = 0.71069 A) radiation. The source is a Mo sealed tube with a 3KW
generator. The frames were integrated in the Bruker SAINT software
package9 and the data were corrected for absorption using the SADABS
program.10 The STR97ll and SHELX-9712 crystallographic software packages
were used. Crystal parameters and basic information pertaining to data
collection and structure refinement are summarized in Tables 4.1-4.5.

(1) {Mn(HzOh[Mn(2,2'-bpym)(H20)]2[Fe(CN)6]2}.. (36)

Single crystals of 36 were grown by layering an aqueous solution of
K3 [Fe(CN)6] with and acetonitrile solution of [(2,2'-bpym)2Mn(HzO)2](BF4)2.
A brown needle-like crystal of dimensions 0.083 x 0.017 x 0.010 mm3 was
mounted on the tip of a glass fiber with Dow Corning silicone grease and
placed in a cold N2 stream. Least squares refinement using well-centered
reflections in the range 3.06° < 20 < 56.66° gave a cell corresponding to a
monoclinic crystal system. A total of 18,980 data (6134 unique) with F(000)
= 1154 were collected at 110(2) K using the 00-20 scan technique to a
maximum 20 value of 56.66°. Systematic absences fiom the data led to the
choice of P21/c as the space group. The final full—matrix, least-squares

refinement was based on data with F.2 > 40(F02) and parameters to give R1 =

193

 

Table 4.1. Crystallographic information for

{Mn(H20)2[Mn(2,2'-bpym)(H20)]2[Fe(CN)6]2 }.. (36) '9H20

 

36 .9H20

 

Empirical formula
Formula weight
Temperature (K)

Space group

a (A)

b (A)

c (A)

a (°)

13 (°)

7 (°)

Volume (A3)

Z

Dca1c(Mg m3)
Absorption coefficient(mm")
Crystal size (mm)
Reflections collected
Independent reflections
Rim

Final R indices

C28H38F62MH3N20013
1 139.30

1 10(2)

P21/c

13.209(3)

26.694(5)

7.443(2)

90

105.57(3)

90

2528.1(10)

2

1.497

1.361

0.083 x 0.017 X 0.010
18980

6134

0.2250

R1 = 0.0715

WR2 = 0.1630

 

R1 = 201131 - IF. ll] / 2113.1. wR2 = {):[w(F,2 — 13.2)2 / 2[w(F02)2]}"2. GOF =
{2[W(F02 - Fc2)2] / (n — p)}“2 where n = total number of reflections and p =

total number of parameters.

Table 4.2. Crystallographic information for {[Co(2,2'-bpy)2]3,[Fe(CN)6]2}+

 

 

(37)
37
Formula C73H71F€2CO3N24013
Formula weight 1926.39

Temperature (K)

Space group

a (A)

b (A)

c (A)

on (°)

13 (°)

Y (°)

Volume (A3)

Z

D... (Mg m3)
Absorption coefficient(mm")
Crystal size (mm)
Reflections collected
Independent reflections
Rim

Final R indices

90(2)
P6322
18.540(5)
18.540(5)
30.7 10(5)
90

90

120

9142(4)

2

1.374

0.918

0.053 x 0.04 x 0.021
59352

7537

0.1494

R1 = 0.067
wR2 = 0.2222

 

R, = 21mm - IF. 11] /21F,1. wR2 = {>:[w(l=.2 — 1:.2)2 / E[w(F.,2)2]}1/2. cor =
{):v[W(Fo2 - Fc2)2] / (n - p)}"2 where n = total number of reflections and p =

total number of parameters.

Table 4.3. Crystallographic information for {[Ni(2,2'—bpy)2(OH2)][ Ni(2,2'-

bPY)212[Fe(CN)612} (38)

 

Formula

Formula weight

38
C73H48F62Ni3N24018

1837.18

Temperature (K) 110(2)

Space group P-l

a (A) 13.251(3)

b (A) 17.678(4)

c (A) 18.057(4)

01 (°) 9457(3)

13 (°) 103.81(3)

7 (°) 9535(3)

Volume (A3) 4066.8(14)

Z 2

Dcalc (Mg m'i') 1.500

Absorption coefficient(mm'l) 1.112

Crystal size (mm) 0.053 x 0.04 x 0.021

Reflections collected 30014

Independent reflections 18520

Rim 0.0729

Final R indices R] = 0.101
wR2 = 0.2543

 

R, = Z[IIF.,I - IF. 11] / 21F.1. wR2 = {2[w(F.2 — 1=."‘)2 / Z[w(F.2)2]}"2. GOF =
{2‘.[w(F.,2 — F.2)2] / (n - p)}“2 where n = total number of reflections and p =
total number of parameters.

196

Table 4.4. Crystallographic information for {[Zn(phen)3][Zn(phen)2]2

[Fe(CN)612} (39) '25H20

 

 

39 025HzO
Formula C96H106Fe2Zn3N26025
Formula weight 2326.54
Temperature (K) 110(2)
Space group C2/c
a (A) 42.047(5)
b (A) 13.541(5)
c (A) 28.781(5)
0L (°) 90
[3 (°) 120.232(5)
7 (°) 90
Volume (A3) 14158(6)
Z 4
D“). (Mg m‘3) 1.354
Absorption coefficient(mm'l) 0.944
Crystal size (mm) 0.175 x 0.047 x 0.011
Reflections collected 22031
Independent reflections 11727
Rim 0.1 126
Final R indices R1 = 0.0997
wR2 = 0.2617

 

R1 = 2[11F.I - IF. 11] / 21F.1. wR2 = (2[w(F.2 — F.2)2 / Z[w(F02)2]}“2, (30F =
{ElMFo2 - Fc2)2] / (n - PHI/2 where n = total number of reflections and p =

total number of parameters.

Table 4.5. Crystallographic information for {[Zn(phen)2][Fe(CN)6] }2
{[Zn(phen)2][Zn(phen)2(OH2)][Fe(CN)6] }2 (40) '19H20'4CH30H

 

40 019H2004CH3OH

 

Formula

Formula weight
Temperature (K)

Space group

a (A)

b (A)

c (A)

(1 (°)

13 (°)

Y (°)

Volume (A3)

Z

D... (Mg 111*)
Absorption coefficient(mm")
Crystal size (mm)
Reflections collected
Independent reflections
Rim

Final R indices

C172H146Fe4zn6N48025
2826.4

1 10(2)

C2/C

48.139(10)
13.585(3)
34.131(7)

90

1 1205(3)

90

206890)

2

1.134

0.726

0.014 x 0.07 X 0.05
75183

24876

0.5283

R1 = 0.0997

WRZ = 0.2185

 

R1 = 21111:.) - IF. 11] /21F.1. wR2 = {2[w(F.2 — 1:.2)2 / 2[w(l=.2)2]}“2. GOF =
{21W(Fo2 - Fc2)2] / (n — p)}“2 where n = total number of reflections and p =

total number of parameters.

0.0715 (wR2 = 0.1630) and Rim = 0.2250. The goodness-of-fit index was
0.856, and the highest peak in the final difference map was 0.957 e‘/A3. All
non-hydrogen atoms were refined anisotropically, except for the disordered
interstitial water molecules. The hydrogen atoms were placed in calculated
positions and treated as riding atoms. A structural representation is depicted
in Figure 4.1.

(2) {Ico(292"bPY)213[Fe(CN)612}+(37)

Single crystals of 37 were grown by layering an aqueous solution of [K-l 8-C-
6]3[Fe(CN)6] with an acetonitrile solution of [Co(2,2'-bpy)3](ClO4)2 in a test
tube. A hexagonal, navy-blue crystal of dimensions 0.053 x 0.04 x 0.021 mm3
was mounted on the tip of a glass fiber with Dow Corning silicone grease and
placed in a cold N2 stream. Least squares refinement using well-centered
reflections in the range 2.54° < 20 < 56.52° gave a cell corresponding to a
hexagonal crystal system. A total of 59352 data (7537 unique) with F(000) =
3834 were collected at 90(2) K using the 00-20 scan technique to a maximum
20 value of 56.52°. Systematic absences from the data led to the choice of
P6322 as the space group. The final full-matrix, least-squares refinement was
based on data with F02>40(F.2) and parameters to give R1 = 0.067 (wR2 =

0.2222) and Rim = 0.1494. The goodness-of-fit index was 1.151, and the

199

 

highest peak in the final difference map was 1.384 e'/A3. All non-hydrogen
atoms were refined anisotropically, except for the disordered interstitial water
molecules. The hydrogen atoms were placed in calculated positions and
treated as riding atoms. A thermal ellipsoid plot is presented in Figure 4.2.

(3) [Ni(ZJ'-bPYh(0H2)l [N i(2,2'-bpy)2]2[Fe(CN)6]2 (33)

Single crystals of 38 were grown by evaporation of a solution in a vial
containing [(2,2'-bpy)2Ni(OH2)2](CF3SO3)2 and K3[Fe(CN)6] that had been
placed near an oven. A dark orange-red crystal of dimensions 0.379 x 0.162 x
0.070 mm3 was mounted on the tip of a glass fiber with Dow Corning silicone
grease and placed in a cold N2 stream. Least squares refinement using well-
centered reflections in the range 2.32° < 20 < 56.54° gave a cell
corresponding to a triclinic crystal system. A total of 30014 data (18520
unique) with F(000) = 1868 were collected at 110(2) K using the 00-20 scan
technique to a maximum 20 value of 56.54°. The space group is P-l. The
final full-matrix, least-squares refinement was based on data with F.2 > 40
(13.2) and parameters to give R1 = 0.101 (wR2 = 0.2543) and R... = 0.0729.
The goodness-of-fit index was 0.909, and the highest peak in the final
difference map was 1.707 e'/A3. All non-hydrogen atoms were refined

anisotropically, except for the disordered interstitial water molecules. The

200

hydrogen atoms were placed in calculated positions and treated as riding
atoms. A structural representation is depicted in Figure 4.3.

(4) [Zn(Phen)3l{[Zn(Phen)zl[Fe(CN)ol}2 (39)

Single crystals of 39 were grown by slow evaporation of the yellow filtrate.
An orange crystal of dimensions 0.175 x 0.047 x 0.110 mm3 was mounted on
the tip of a glass fiber with Dow Corning silicone grease and placed in a cold
N2 stream. Least squares refinement using well-centered reflections in the
range 8.36° < 20 < 51.08° gave a cell corresponding to a monoclinic crystal
system. A total of 22031 data (11727 unique) with F(000) = 5864 were
collected at 110(2) K using the 03-20 scan technique to a maximum 20 value
of 51.08°. Systematic absences from the data led to the choice of C2/c as the
space group. The final lull-matrix, least-squares refinement was based on data
with F.2 > 40(F02) and parameters to give R1 = 0.997 (wR2 = 0.2617) and
R... = 0.1126. The goodness-of-fit index was 1.083, and the highest peak in
the final difference map was 2.081 e'/A3. All non-hydrogen atoms were
refined anisotropically, except for the disordered interstitial water molecules.
The hydrogen atoms were placed ill calculated positions and treated as riding

atoms. A structural representation is presented in Figure 4.4.

(5){[Zn(Phen)zl [Fe(CN)ol}2{Zn(Phen)21 [Zn(Phen)2(0H2)l [F 9(CN)6112 (40)

201

Single crystals of 40 were grown by slow diffusion of an aqueous solution of
K3 [Fe(CN)6] into a methanol solution of (phen);Zn(NO3)2. A yellow crystal of
dimensions 0.014 x 0.07 x 0.05 mm3 was mounted on the tip of a glass fiber
with Dow Corning silicone grease and placed in a cold N2 stream. Least
squares refinement using well-centered reflections in the range 2.54° < 20 <
56.64° gave a cell corresponding to a monoclinic crystal system. A total of
75183 data (24876 unique) with F(000) = 7392 were collected at 110(2) K
using the 00-20 scan technique to a maximtun 20 value of 56.64°. Systematic
absences from the data led to the choice of C2/c as the space group. The final
full-matrix, least-squares refinement was based on data with F02>4G(F02) and
parameters to give R1 = 0.099 (wR2 = 0.2185) and R... = 0.5283. The
goodness-of-fit index was 0.678, and the highest peak in the final difference
map was 1.018 e'/A3. All non-hydrogen atoms were refined anisotropically,
except for the disordered interstitial water molecules. The hydrogen atoms
were placed in calculated positions and treated as riding atoms. A structural

representation is presented in Figure 4.5.

202

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Figure 4.2. Thermal ellipsoid plot of {[Co(2,2'—bpy)2]3,[Fe(CN).5]2}+ (37) at
the 50 % probability level. The hydrogen atoms were omitted for
the sake of clarity. (Image is presented in color)

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3. RESULTS AND DISCUSSION

A. Syntheses

(1) {Mn(Hzoh[Mn(2,2'-bpym)(H20)]2[Fe(CN)6]2}( (36) '9H20

Brown single crystals of {Mn(HzO)2[Mn(2,2'-bpym)(H20)]2[Fe(CN)6]2},o
were grown by slow diffusion of an acetonitrile solution of [(2,2'—bpymth
(0H2)2](BF4)2 into an aqueous solution of K3[Fe(CN)6]. The same brown
needle-like crystals were obtained by replacing [(2,2'—bpym)2Mn
(0H2)2](BF4)2 with [(2,2'—bpym)2Mn(OH2)2]SO4. The reaction of three
equivalents of [(2,2'-bpym)2Mn(OH2)2](BF4)2 with two equivalents of
K3[Fe(CN)6] yields a brown precipitate and a yellow solution. After the
yellow solution had been slowly evaporated, brown crystals were obtained.
The crystals, however, are not of a quality suitable for single crystal X-ray
diffi'action. IR data collected on both the brown crystals and the
polycrystalline sample support the conclusion that the compounds are the
same. Once the crystals and the polycrystalline sample had been washed with
water, a pale yellow filtrate was obtained which produced yellow crystals that
were identified by X-ray methods as being K3[Fe(CN)6](2,2'-bpym)5(H20)5.
Elemental analysis on the polycrystalline sample did not fit well with the

formula obtained from the single crystal data. The TGA data of the

208

polycrystalline sample yielded only 5 water molecules being released instead
of 13 water molecules.

Attempts to synthesize the polymeric product from the combination of
three equivalents of MnSO4o7H20 with two equivalents of K3 [Fe(CN)5] and
one equivalent of 2,2'—bpym in water did not succeed. The reaction yielded a
brown/yellow precipitate that was washed with water followed by acetone.
The IR data reveal cyanide stretches at 2196 (w), 2147 (m), 2083 (w), 2062
(W) cm'1 which are at higher energies than the ones identified for bona fide
batches of {Mn(I-120)2[Mn(2,2'-bpym)(H20)]2[Fe(CN)6]2}a, (36) 09H20.

(2) {[Co(2,2'-bpy)2]3[Fe(CN)6]2}+ (37)

All nine reactions described in sections 2A-I were performed by adding the
cobalt starting material into the solution of the hexacyanoferrateall) anion. In
all cases, the result was the formation of a navy blue precipitate. The IR data
summarized in Tables 4.6 and 4.7 reveal that the seven reactions performed in
50 mL of water (regardless of the presence or absence of air) yield products
with four v(C-=-N) stretches at (~ 2139, 2108, 2096 and 2067 cm"). IR data
summarized in Table 4.7 also indicates the remaining two reactions between
[Co(2,2'-bpy)3](ClO4)2 or [(2,2'-bpy)2Co(CF3SO3)2] and [K-l8-C-

6]3[Fe(CN)6] in a 3:2 ratio in either acetonitrile or methanol gave rise to three

209

v(C:-:N) stretches at ~2138, 2106, 2060 cm". X-ray powder diffraction, SEM
and Mossbauer studies were performed on selected samples in these studies.
SEM and X-ray powder difli'action data clearly indicate that the reactions
performed in water are more crystalline (Figure 4.6). The reactions carried
out in acetonitrile or methanol led to essentially amorphous products as
indicated by SEM and X-ray powder diffraction. Room temperature
Mossbauer data for the eight prodcuts of reactions 2B-I indicate that all the
Fe atoms are divalent. The isomer shifts and and quadrupole splittings are
summarized in Table 4.8.

The preferred method for growing crystals of {[Co(2,2'-
bpy)2]3[Fe(CN)6]2}+ is to layer an aqueous solution of [K-lS-C-6]3[Fe(CN)6]
with an acetonitrile solution of either [Co(2,2'-bpy)3](ClO4)2 or (2,2'-
bpy)2Co(CF3803)2. Slow diffusion reactions of this type were set up in 6-8 m
diameter glass tubes as well as in various sizes of test tubes. In all of these
cases, large well-formed yellow crystals were obtained. These yellow crystals
invariably were [(2,2'-bpy)2Co(CN)2](C104) or [(2,2'-bpy)2Co(CN)2](CF3SO3)
as evidenced by single crystal X-ray diffraction. This result points out the

ease with which Co" atoms oxidize to CoIII in these reactions.

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(3) [Ni(2,2'-bPY)2(0H2)l[Ni(2,2'-bPY)2]2[Fe(CN)s]2 (38)

When three equivalents of [(2,2'-bpy)2Ni(OH2)2](CF3SO3)2 were combined
with 2 equivalents of K3[Fe(CN)6] in water, an initial yellow/brown
precipitate formed. IR data of the yellow/brown precipitate revealed v(CaN)
stretches located at 2142 and 2113 cm'1 and ligand v(C=C) and v(C=N)
stretches for 2,2'—bpy at 1604 1598, 1575 and 1567 cm']. The yellow filtrate
from this reaction was evaporated in a warm place in the lab (next to an oven)
which led to the slow grth of dark orange/brown crystals admixed with a
yellow/brown precipitate. A single crystal X-ray diffiaction study identified
the crystals to be the pentameric compound [N i(2,2'-bpy)2(OH2)] [Ni(2,2'-
bpy)2]2[Fe(CN)6]2 (38). Attempts to grow crystals by slow difliasion of
aqueous K3[Fe(CN)6] with [(2,2'-bpy)2Ni(OH2)2](CF3SO3)2 in acetonitrile led
to yellow precipitate and tiny orange crystals.

(4) [Zn(Phen)sl{[Zn(Ph¢n)2l[Fe(CN)6]}2 (39)

An aqueous solution of (phen)ZZn(NO3)2 (3 equiv) was reacted with
K3[Fe(CN)6] (2 equiv) to yield a yellow precipitate whose IR spectrum
contains v(CEN) modes at 2150, 2113 and 2062 cm" and 1,10-
phenanthroline v(C=C) and v(C=N) stretches at 1623 and 1579 cm". When

the yellow filtrate was slowly evaporated, orange trigonal-shaped crystals of

215

the tetrameric compound [Zn(phen)3] { [Zn(phen)2] [F e(CN)6] } 2 were obtained.
IR spectral properties of the orange crystals indicate the presence of v(CEN)
stretches at 2151, 2143, and 2127 and 2108 cm" and v(C=C) and v(C=N)
modes at 1623 and 1578 cm'1 for the 1,10-phenanthroline ligand. The IR data
for the yellow precipitate and orange crystals are very similar.

Additional studies on this reaction were carried out in attempts to grow
crystals of the main product(s). Slow diffusion reactions were set up in 6 mm
diameter tubes with an aqueous layer of hexacyanoferrate(IH) on the bottom
and a methanol solution of (phen)ZZn(NO3)2 on top. These slow diflilsions
resulted in the formation of rectangular yellow crystals which are the unusual
decameric compound { [Zn(phen)2][Fe(CN)5]}2{[Zn(phen)2]-
[Zn(phen)2(OH2)][Fe(CN)6]}2 (40) as determined by single crystal X-ray
diffiaction methods.

B. Reactions

(1) Reaction of (2,2'-bpy)2Mn(CF3SO3)2 with [K-18-C-6]3[Fe(CN)6]

The manganese complex was added directly to a solution of
hexacyanoferrate(IH) to give a brown precipitate with v(CEN) stretches at

2143 (s), 2119 (m) and 2063 (m) cm". Based on our experience with the

compound {Mn(H20)2WH(2,2'-bpym)(H20)]2[Fe(CN)6]2}ao (36), the V(CEN)

216

mode at 2146 cm’1 is assigned to the Fem oxidation state and the activity at
1622 (m) and 1590 (m) cm’1 is assigned to v(C=C) and v(C=N) stretches of
the 2,2'-bipyridine ligand. Attempts to grow crystals by layering [K-18-C-
6]3[Fe(CN)5] in methanol with (2,2'—bpy)2Mn(CF3SO3)2 in acetonitrile were
performed in 6-8 mm diameter glass tubes and test tubes, but no crystals were
observed to form. A list of the cyanide stretches from various reactions is
provided in Table 4.9.

(2) Reaction of (2,2'-bpy)2Mn(CF3SO3)2 and K3[Fe(CN)5]

These reactions were performed in water with different ratios of the starting
materials. Equimolar quantities of each reactant 50 mL of water gave a
brown precipitate which had a very complicated v(CEN) region: 2155 (w),
2142 (s), 2133 (s), 2122 (s), 2112 (s), 2078 (w), 2061 (w) and 2038 (w) cm".
According to the results of the previous section, the use of [K-18—C-
6]3[Fe(CN)6] in acetonitrile/methanol gave a product with only one strong
stretch at 2143 cm". This species may be forming in water, but there are
many other products as well. The second reaction of this type was performed
in a 3:2 ratio in 30 mL of water, which led to the deposition of a brown
precipitate with numerous cyanide stretches as indicated by the IR data. It is
obvious that more than one product is forming in these reactions. A

comparison of the IR data for different reactions is provided in Table 4.9.

217

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(3) Reaction of [Mn(2,2'-bpy)3](ClO4)z with K3[Fe(CN)6]

The reaction of equimolar quantites of [Mn(2,2'-bpy)3](ClO4)2 and
K3[Fe(CN)6] in 80 mL of water led to the formation of in a brown precipitate
with cyanide stretches at 2136 (m), 2120 (s) and 2057 (m) cm“. The
presence of 2,2'-bipyridine was indicated by the v(C=C) and v(C=N)
stretches at 1594 (s), 1575 (m) 1565 (m) cm". Attempts to grow crystals by
layering an aqueous solution of K3[Fe(CN)6] with [Mn(2,2'-bpy)3](ClO4)2 in
acetonitrile in 6 mm glass tubing led to the isolation of brown needles.
Although the crystals were small and diffracted poorly, an X-ray data set was
collected which led to the identification of the product as
{Mn(H20)2[Mn(ZaT-bpmeHzOHz[Fe(CN)6]2}co (36) This Polymeric
material is identical to the 2-D structure with 2,2'-bpym ligand, and it's
isolation with 2,2'-bpy ligand indicates that it is a stable, persistent
architecture.

(4) Reaction of [Mn(2,2'-bpy)3](ClO4)2 with [K-18-C-6]3[Fe(CN)6]

A 3:2 ratio of [Mn(2,2'-bpy)3](ClO4)2 and [K-18-C-6]3[Fe(CN)6] in 100 mL
of acetonitrile was refluxed for three days to give a brown precipitate with
three v(CEN) stretches at 2146 (s), 2118 (m) and 2064 (m). This is essentially

the same cyanide infrared stretching pattern observed for {Mn(H20)2[Mn

219

(2,2'-bpym)(H20)]2[Fe(CN)6]2}.0 (36).
(5) Reaction of (phenth(CF3SO3)2 and [Fe(CN)6]3'

Reactions between of (phen)2Mn(CF3SO3)2and [Fe(CN)6]3' were performed
with different ratios of reactants and in different solvents. Three equivalents
of (phen)2Mn(CF3SO3)2 in a mixture of water and methanol were added to
two equivalents of K3[Fe(CN)6] dissolved in water to give a brown
precipitate. IR data in the v(CaN) region are 2142 (w), 2113 (m), 2090 (w),
2053 (w, br) cm". The presence of 1,10-phenanthroline was noted by the
v(C=C) and v(C=N) stretches located at 1589 (m) and 1574 (m) cm". A 1:1
ratio of (phen)2Mn(CF3803)2 with [K-18-C-6]3[Fe(CN)6] in water led to the
formation of a yellow/brown precipitate with v(CEN) modes at 2142 (w) and
2112 (m) cm‘1 and C=C and C=N stretches (1589 (m) and 1573 (m) cm") for
1,10-phen. A third reaction of this type was performed with a 3:2 ratio of
(phen)2Mn(CF3SO3)2 and [K-18-C-6]3[Fe(CN)6] in a mixture of acetonitrile
and methanol. The reaction yielded a brown precipitate with cyanide stretches
located at 2143 (w), 2114 (m) and 2067 (w, br) cm'1 and 1,10-phen C=C and
C=N stretches at 1590 (m) and 1572 (m) cm'1 in the IR data. A comparison of
the IR data for cyanide region is presented in Table 4.10. In all three of these

reactions, the prominent v(CEN) stretch is at ~2113 cm". The 2-D strong

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stretch as higher energies, namely 2146 cm", which implies that the use of the
1,10-phen ligand leads to a different structure than the one with 2,2'-bpym.
Unfortunately, attempts to crystallize this product were not successful.

(6) Reaction of [Co(2,2'-bpym)3](BF4)2 with [K-l8-C—6]3[Fe(CN)6]
Mixtures of [Co(2,2'-bpym)3](BF4)2 and [K-18-C-6]3[Fe(CN)6] in a 3:2 ratio
in acetonitrile did not react even after refluxing the reaction for three days.
After three days, a few drops of water were added which led to the deposition
of a purple precipitate in an intensely colored purple solution. An IR spectrum
of the purple solid in the v(CaN) region revealed stretches at 2141 (w), 2119
(m) and 2068 (s) cm". The presence of the 2,2'-bipyrimidine ligand was
indicated by the v(C=N) stretches located at 1576 (s) and 1560 (m) cm'1 in
the IR. In comparison, {[Co(2,2'-bpy)2]3[Fe(CN)6]2}+ (37), displays a strong
cyanide stretch at ~2066 cm". In (37), the metal ion oxidation states are Com
and F e“. From this, it is logical to conclude that the same oxidation states are
present in the purple product as well.

(7) Reaction of [Co(2,2'-bpym)3](BF4)2 with K3[Fe(CN)5]

This reaction was performed in deoxygenated water in a 3:2 ratio of [Co(2,2‘-
bpym)3](BF4)2 and K3[Fe(CN)6]. Upon mixing, the solution color

instantaneously turned to an intense purple color and a filmy solid was

222

isolated by filtration in air. The v(CaN) stretches for the product are located
at 2117 (s) and 2074 (s, br) cm", and the presence of 2,2'-bpym was
confirmed by the v(C=N) stretches at 1580 (s), 1575 (s) and 1557 (s) cm".
As mentioned in the previous section, it is postulated that this product
contains CoIII and Fe‘1 since the cyanide stretches appear at lower energies
than what is observed for Co11 and FeIII combinations. Attempts to grow
crystals by layering an aqueous solution of K3[Fe(CN)6] with [Co(2,2'-
bpym)3](BF4)2 invariably led to a gelatinous purple product.

(8) Reaction of (phen)¢C0(NO3)2 with K3[Fe(CN)6]

Reactions of (phen)2Co(NO3)2 and K3 [F e(CN)6] (3 :2 ratio) in water lead to
the formation of a green precipitate regardless of whether the reaction is
performed in air or the absence of air. The filtrate for the reaction performed
under nitrogen was pale green, while the reaction performed in air yielded a
pale blue colored filtrate. Both green solids exhibit essentially the same
cyanide stretches at ~2108 and 2076 cm". The IR data also indicate the
presence of the 1,10-phenanthroline ligand. A compilation of IR data in the
v(CsN) region is summarized in Table 4.11. Crystal growing attempts

included layeringa solution of K3 [Fe(CN)6] in H20 with a CH3OH

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solution of (phen)2Co(NO3)2. Hexagonal-shaped blue crystals formed as well
as very thin blue needle-like crystals. Unfortunately, these crystals were not
of a quality sufficient to collect a single-crystal X-ray data set.

(9) Reaction of [TpCo(CH3CN)3](PF6) with [K-l8-C—6]3[Fe(CN)5]
Equimolar quantitites of each reactant were combined in 50 mL of acetonitrile
to give a blue/green solution with no precipitate. The lack of a precipitate
indicates that the product is product is probably not a polymer or a neutral
material, but rather a charged molecule. IR data revealed the presence of two
cyanide stretches at 2109 (s) and 2064 (8, br) cm". The low energies indicate
that the product contains Com and F e". The solution was slowly evaporated
under a nitrogen purge, but unfortunately no crystals were obtained. A small
amount of the acetonitrile solution was placed in a 5 mL vial without a cap
and placed inside of a capped 20 mL vial that contained diethyl ether, but this
attempt also failed to yield crystals.

(10) Reaction of (dien)Ni(N03)2 with [K-18-C-6]3[Fe(CN)6]

Equimolar solutions of each reactant were dissolved in a mixture of
acetonitrile and methanol, which led to a dark orange/brown colored solution.
The IR spectrum of the product contains two cyanide stretches at 2149 (m)

and 2101 (s) cm". All attempts to grow crystals of the product by slow

225

evaporation and slow diffusion of diethyl ether into the reaction solution led

only to powders.

(11) Reaction of [(2,2'-bpy)2Ni(OH2)2](CF3SOg)2 with
[K-18-C-613[F6(CN)61

A 3:2 ratio of [(2,2'-bpy)2Ni(OH2)2]( CF3SO3)2 to [K-18-C-6]3[Fe(CN)6] in 50

mL of acetonitrile was refluxed overnight to yield a yellow/brown precipitate.

The IR spectrum contains v(CEN) features at 2156, 2144, 2112 and 2107

cm", and v(C=C)/v(C=N) features of 2,2'-bpy at 1599, 1576, 1567 cm".

(12) Reaction of [(2,2'-bpy)2Ni(CH3CN)2](PF6)2 with K3[Fe(CN)6]

Three equivalents of [(2,2'-bpy)2Ni(CH3CN)2](PF6)2 in an acetonitrile solution

were combined with the K3[Fe(CN)6] in a mixture of acetonitrile and water to

give a brown precipitate with v(C=_=N) modes at 2148 (s), 2126 (m) and 2087

(m) cm". The 2,2'-bpy ligand was evident by the v(C=C)/v(C=N) stretches at

1585 (m) and 1578 (m) cm".

(13) Reaction of [(phenth(N03)z with K3[Fe(CN)6] in various ratios

Aqueous solutions of (phen)2Zn(NO3)2 and K3 [Fe(CN)6] were reacted in a 3:2

ratio to yield a yellow precipitate with v(C.=.N) stretches at 2147 (m), 2114

(m) and 2077 (m) cm‘1 for the reaction performed in 50 mL of water. The

reaction performed at lower concentrations (100 mL) exhibited similar

226

cyanide stretches at 2151 (m), 2114 (m) and 2062 (w) cm". The 1,10-
phenanthroline ligand activity was evident by stretches at 1623 (m), 1585 (m)
and 1578 (m) cm" for the 50 mL reaction and at 1626 (m) and 1577 (m) cm'I
for the 100 mL reaction. These IR data indicate that the reactions lead to the
same yellow product. A 1:1 and a 4:] reaction of (phen)2Zn(NO3)2 and
K3[Fe(CN)6] also yield yellow precipitates, but the IR data are more
complicated, indicating that more than one product is being formed. A
comparison of the IR data of the cyanide stretching region for these four
reactions is in Table 4.12.

(14) Reaction of (phen)2Zn(NO3)2 with K4[Fe(CN)6] in various ratios

The reaction of (phen)2Zn(NO3)2 and K4[Fe(CN)6] in a 3:1 ratio produces a
gelatinous yellow/orange product with cyanide stretches located at 2056 (s)
and the signature of 1,10-phen at 1623 (m) and 1579 (m) cm". When the
ratio of reactants was changed to 3 :2, a pale yellow/white gelatinous product
was obtained which exhibits only one v(CEN) stretch at 2074 (5, br) em". IR
data of these two reactions are summarized in Table 4.12.

(15) Reaction of (phenthClz with K3[Fe(CN)6]

These reactions were performed in a 3:2 ratio of the reactants in both 50 mL
and 100 mL of water. In both reactions, a yellow precipitate formed with

v(C=C) and v(C=N) stretches from the 1,10-phenanthroline ligand located at

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1624 and 1579 cm'1 in the IR. Both reactions led to products with similar
cyanide stretches. The IR data is summarized in Table 4.13.

(16) Reaction of [Zn(phen)3]Cl2 and K3[Fe(CN)6]

Reactions performed in a 3:2 ratio of the reactants in both 50 mL and 100 mL
of water lead to yellow gelatinous products with numerous cyanide stretches
in the IR spectrum (Table 4.13).

(17) Reaction of (2,2'-bpy)2Zn(NO3)2 and K3[Fe(CN)6]

A 3:2 ratio of the reactants in H20 leads to the immediate production of a
yellow precipitate with v(CEN) modes located at 2177 (s), 2168 (s), 2162 (s),
2124 (m), 2114 (m), 2108 (m) and 2085 (s) cm". The presence of 2,2'-
bipyridine was evident from the v(C=C)/v(C=N) stretches located at 1607,
1597, 1577 and 1567 cm". The complicated nature of the v(CsN) region is
indicative of the formation of several products and possibly mixed Fem and
Fe‘1 oxidation states.

(18) Reaction of (2,2'-bpy)2Zn(NO3)2 and K4[Fe(CN)5]

The reactants were combined in a 3:2 ratio to yield a gelatinous yellow
product in water. The IR data revealed v(CEN) modes located at 2085, 2062,
2048, and 2034 cm".

(19) Reaction of (2,2'-bpy)2ZnCl2 and K3[Fe(CN)5]

230

An aqueous solution of 3 equivalents of (2,2'-bpy)2ZnClz were combined with
two equivalents of K3 [F e(CN)6] to give a yellow precipitate with v(CEN)
stretches at 2162 and 2090 cm'1 and v(C=C)/v(C=N) modes at 1607, 1598,
1578 and 1568 cm'1 for the 2,2'-bpy ligand.

(20) Reaction of (2,2'-bpy)zZnC|2 and K4[Fe(CN)5]

The reactants were combined in a 3:2 ratio to yield a pale yellow/white
gelatinous material in water. The product exhibited v(CsN) stretches at 2160,
2097, 2086 and 2061 cm'1 and v(C=C)/v(C=N) modes at 1605, 1596 and
1576 cm'1 for the 2,2'-bpy ligand.

C. Molecular Structures

(1) {Mn(Hzoh[Mn(ZJ'-bpym)(H20)lz[Fe(CNklzle (36)

The asymmetric unit of the structure consists of one [Fe(CN)6]3‘ unit
connected to two different types of Mn11 centers via cyanide bridges. One Mn
atom (Mn2) has retained only one 2,2‘-bpym ligand while the other one
Mnl) has lost both of its original 2,2'-bpym ligands. For simplicity in
describing the repeat pattern, the building blocks of the layers are defined as
[Fe(CN)6]3' (Fel), trans-[Mn(0H2)2]2+ (Mnl) and fac-[Mn(2,2'—
bpym)(OH2)]2+ (Mn2) units. Each Fem ion forms bridges to three Mn2 and

two Mnl centers, which leaves behind one terminal CN' ligand. The trans-

231

[Mn(OH2)2]2+ units are linked to four Fem ions, and each fac-[Mn(2,2'-
bpym)(OH2)]2+ building block is connected to three independent [Fe(CN)6]3'
anions. The resulting polymeric fi'amework is best described as being
composed of individual l-D chains formed by edge-sharing {[Mn(2,2'-
bpym)(OH2)]2[Fe(CN)6]2} squares. These chains, which exhibit a staircase
motif, are stitched into layers by trans-[l\'1n(OH2)2]2+ bridges that serve to link
Fe atoms of adjacent chains and to create two new comer-sharing {[Mn(2,2'-
bpym)(OH2)][Fe(CN)6]2-[Mn(OH2)]2} squares (Figure 4.7a). A simplified
diagram of this structure, depicted in Figure 4.7b, reveals that the fiamework
resembles a 2-D array of fused Mn4Fe3 cubes missing one vertex. It is of
fi1rther interest to point out that the 2,2'-bpym ligands of adjacent layers are
interdigitated to form a stacked column along the c axis with a mean spacing
of 3.35 A (Figure 4.8.). The bond distances and bond angles are summarized
in Tables 4.14 and 4.15.

(2) {[C0(2,2'-bPY)213[Fe(CNkle (37)

The structure consists of two [Fe(CN)6]3' units, each connected to three ColII
centers in a facial arrangement by cyanide bridges. Each pseudo-octahedral
Com atom is composed of two 2,2'-bpy ligands, with the remaining two sites
being filled by the nitrogen end of the cyanide ligand from the [Fe(CN)6]3‘

units. The Co-N(2,2'-bpy) distances are in the range 1.847(9)«l 953(8) A.

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Table 4.14. Selected bond distances [A] for
{Mn(H20)2[Mn(2,2'-bpym)(H20)]2[Fe(CN)6]2} (36)

 

 

A A-B [A]

Mn(l) N(5) 2.177(10)
Mn(l) 0(1) 2.187(12)
Mn(l) N(6) 2.193(11)
Mn(2) N(3) 2. 152( 10)
Mn(2) N(4) 2.148(13)
Mn(2) N (2) 2.166(10)
Mn(2) 0(2) 2.282(8)

Mn(2) N(8) 2.296(1 1)
Mn(2) N(7) 2.275(10)
Fe(l) C(5) 1.912(13)
Fe(l) C(3) 1.953(12)
C(l) N(l) 1.157(17)
C(3) N(3) 1.131(13)
C(5) N(5) 1.173(14)

235

Table 4.15. Selected bond angles [°] for

{Mn(H20)2[Mn(2,2'-bpym)(H20)]2[Fe(CN)6]2 } (36)

 

 

A B C A-B-C [°]
N(7) Mn(2) N (8) 715(4)

C(2) N (2) Mn(2) 172.0(10)
C(3) N (3) Mn(2) 174.5(12)
C(4) N(4) Mn(2) 169.4(11)
C(5) N(5) Mn(l) 179.7(15)
C(6) N(6) Mn(l) 174.1(11)
N(l) C(l) Fe(l) 178.4(15)
N (2) C(2) Fe(l) 177.8(13)
N(5) C(5) Fe(l) 176.3(11)
N(6) C(6) Fe(l) 177.4(1 1)

236

The bite angles for the 2,2'-bpy ligands are 82.0(4) and 82.7(4)°. The Fe-
C(cyanide) bond distances are in the range l.868(13)—1.949(12)A. Bond
distances and angles are given in Tables 4.16 and 4.17. Top and side views of
the molecule are depicted in Figure 4.9 and the packing diagram is shown in
Figures 4.10.

(3) [Ni(2,2'-bPY)2(0H2)l[Ni(2,2'-bPY)2]2[Fe(CN)clz (38)

The structure of 38 consists of two [Fe(CN)6]3' units connected to two
(bpy)2NiII centers to give a molecular square. One of the [Fe(CN)6]3' units is
connected to two Nin centers within the molecular square and is further
coordinated to a third NiII molecule which contains two bpy ligands and a
H20 molecule. Bond distances and angles are given in Table 4.18 and 4.19.
The packing of this structure is presented in Figure 4.11.

(4) [Zn(Phen)3l [Zn(Phen)2]2 [F e(CNN: (39)

The structure of this compound is a molecular square with alternating
[Zn(phen)2]2+ and [Fe(CN)6]3' units connected by cyanide bridges. Each
[Fe(CN)6]3' possesses four terminal CN' ligands. The molecular square is
anionic and therefore the [Zn(phen)3]2+ cation is present for charge neutrality.
The Zn-N(phen) bond distances are in the range 2.081(13)—2.265(13)A. The

bite angles for the phen ligand are in the range 742(5)-

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Figure 4.10. Packing of the molecules in {[Co(2,2'-bpy)2]3[Fe(CN)(,]2}+ (37)
along the c axis. (Image is presented in color)

239

Table 4.16. Selected bond distances [A] for {[Co(2,2'-bpy)2]3[Fe(CN)6]2 }+

(37)

 

 

A B A-13 [A]
Co(1) N (6) 1.879(8)
Co(1) N (10) 1.906(8)
Co(1) N(9) 1.953(8)
Co(4) N(7) 1 .847(9)
Co(4) N(8) 1.928(9)
Co(4) N( l 6) 1.927(10)
Fe( 1) C( 100) 1.93(3)
Fe(2) C(22) 1.879(12)
Fe(2) C( l) 1.949(12)
Fe(3) C(26) 1.868(13)
Fe(3) C(59) 1.888(10)
C(l) N(l) 1.136(12)
C(59) N(6) 1.191(11)
C(22) N(7) 1.216(13)
C(100) N(lOO) 135(3)

240

Table 4.17. Selected bond angles [°] for {[Co(2,2'-bpy)2]3[Fe(CN)6]2}+ (37)

 

 

A B C A-B-C [°]
N(9) Co(1) N( 10) 82.0(4)
N(8) Co(4) N(16) 82.7(4)
C(59) N(6) Co( 1) 161.8(7)
C(22) N(7) Co(4) 165.3(7)
N(7) C(22) Fe(2) 172.9(8)
N(l) C(l) Fe(2) 177.5(11)
N(60) C(26) Fe(3) 173.3(11)
N (6) C(59) Fe(3) 174.0(9)
N( 100) C( 100) Fe( 1) 172(2)

241

Table 4.18. Selected bond distances [A] for
{ [Ni(2,2"bPY)2(H20)][Ni(2,2"bPY)2]21FC(CN)612l (38)

 

 

A B A-B [A]
Ni(l) N(2) 2.1 19(6)
Ni(l) N(3) 2.081(8)
Ni( 1) N(15) 2.047(7)
Ni(2) N (5 ) 2.099(7)
Ni(2) N(6) 2.068(8)
Ni(2) N(16) 2.065(8)
Ni(5) N(21) 2.037(8)
Ni(5) N (24) 2.080(7)
Ni(5) 0(100) 2.104(6)
Fe( 1) C(52) 1.925(8)
Fe( 1) C(48) 1.950(9)
Fe(2) C(46) 1.946(8)
Fe(2) C(44) l .963 (9)
C(46) N(9) l. 164(10)
C(49) N(16) 1.149(11)

242

Table 4.19. Selected bond angles [°] for
{[Ni(2,2'-bPY)2(H20)][Ni(2,2'-bPY)2]2[Fe(CN)el2} (38)

 

 

A B C A-B-C [°]
N(3) Ni( 1) N (4) 78.4(3)
N( 14) Ni( 1) N(15) 90.4(3)
N(7) N i(2) N(8) 78.1(3)
N (9) Ni(2) N (16) 89.9(3)
N (22) Ni(5) N (23) 78.6(3)
N(21) Ni(5) 0(100) 86.2(3)
C(47) N(15) Ni(l) 169.3(7)
C(49) N (16) Ni(2) 171.3(7)
C(52) N(21) Ni(5) 151.4(7)
N(21) C(52) Fe( 1) 172.7(8)
N(16) C(49) Fe( 1) 174.1(8)
N(9) C(46) Fe(2) 175.9(8)
N(12) C(42) Fe(2) 178.5(8)

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77.2(5)°. The Fe—C(cyanide) bond distances are in the range 1.882(15)—
l.99(2)A. The non-linearity of the cyanide ligands in this molecular square
(as clearly illustrated in Figure 4.4.) is attributed to packing effects that
involve [Zn(phen)3]2+ and the 1,10-phenanthroline ligands that cap the anionic
square. A packing diagram of the molecular square along with the cation is
presented in Figure 4.12. Bond distances and angles are presented in Table
4.20 and 4.21.

(5){[Zn(Phen)2] [F e(CNN}2{ZII(I1|I¢?II)2I [Zn(Phen)2(0H2)l [Fe(CN)sl}2 (40)
This molecular structure of this compound (Figure 4.5) is a very unusual
decamer that results from the addition of [Fe(CN)6]3' and [Zn(phen)2]2+ units
to the molecular square [Zn(phen)3][Zn(phen)2]2[Fe(CN)6]2. The square is
composed of two [Fe(CN)6]3' units connected to two [Zn(phen)2]2+ by
cyanide bridges in a cis arrangement but, the molecule grows by further
addition of [Zn(phen)2]2+ and [Fe(CN)6]3' units through trans cyanide
linkages. Bond distances and angles are presented in Tables 4.22 and 4.23.
The space filling plot of (40) is presented in Figure 4.13.

D. Magnetic Data

(1) {Mn(Hzoh[Mn(2¢'-bpym)(H20)lz[Fe(CN)s]2}ao (36)

245

Table 4.20. Selected bond distances [A] for
{[Zn(Phen)3][Zn(phen)2]2[Fe(CN)6]2} (39)

 

 

A B A-B [A]
Zn(1) N(2) 2.186(13)
Zn(1) N(4) 2.091(13)
Zn(2) N(1 1) 2.065(15)
211(2) N(8) 2.266(14)
Fe(3) C(66) 1.933(17)
Fe(3) C(64) 1.95(2)
Fe(3) C(62) 1.97(2)
Fe(3) C(61) 1.873(17)
C(66) N(16) 1.143(18)
C(63) N(13) 1.123(2)
C(64) N(14) 1.164(19)
C(62) N(1 1) 1.126(18)

246

Table 4.21. Selected bond angles [°] for

{[Zn(Phen)3][Zn(Phen)2]2[Fe(CN)6]2} (39)

 

 

A B C A-B-C [°]
N( 1) Zn( 1) N(23) 76.6(6)
N(3) Zn( 1) N(2) 77.2(5)
N(5) Zn( 1) N(4) 76.8(5)
N(7) Zn(2) N(8) 73.9(6)
N(9) Zn(2) N( 10) 75.0(6)
C(61) N(12) Zn(2) 162.9(12)
C(62) N (1 1) Zn(2) 162.9(14)
N(16) C(66) Fe(3) 176.8(15)
N(13) C(63) Fe(3) 177.6(16)
N(1 1) C(62) Fe(3) 176.1(17)

247

 

Figure 4.12. View of the packing diagram of {[Zn(phen)3][Zn(phen)2]2
[Fe(CN)5]2} (39) down the b axis. (Image is presented in color)

248

Table 4.22. Selected bond distances [A] for
{ [Zn(Phen)2][Fe(CN)6] }2{ [Zn(Phen)2][Zn(Phen)2(0H2)][Fe(CN)6] }2 (40)

 

 

A B A-13 [A]
Zn(l) N(12) 2.077(13)
Zn(l) 0(1) 2.203(10)
Zn(2) N(6) 2.071(13)
Zn(2) N(16) 2.229(10)
Zn(3) N(7) 2.088(12)
Zn(3) N(120) 2.191(13)
Fe(4) C(57) 1.981(16)
Fe(4) C(68) 1.908(15)
Fe(S) C(29) 1.98(2)
Fe(S) C(81) 1.883(16)
C(82) N (86) 1.147(17)
C(67) N (5) 1.132(16)
C(57) N(205) 1.102(16)
C(49) N(1) 1.169(18)
C(39) N(81) 1.175(18)

249

Table 4.23. Selected bond angles [°] for

{ [Zn(phen)2][Fe(CN)6] }2{ [Zn(phen)2] [Zn(phen)2(OH2)][Fe(CN)6] }2 (40)

 

 

A B C A-B-C [°]
N(121) Zn(l) N(122) 78.6(5)
N(2) Zn(l) N(14) 78.8(5)
N(9) Zn(2) N(IO) 76.5(5)
N (8) Zn(2) N(16) 75.4(4)
N( 15) Zn(3) N(120) 75.7(5)
C(81) N(12) Zn(l) 145.7(13)
C(37) N(6) Zn(2) 163.1(12)
C(82) N(86) Zn(2) 147.0(12)
C(68) N(7) Zn(3) 173.6(12)
N(7) C(68) Fe(4) 175.5(12)
N(5) C(67) Fe(S) 175.1(13)
N (13) C(69) Fe(5) 176.3(13)

250

 

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251

The molar susceptibity 1m between 50 and 300 K was fit to a Curie-Weiss

law with C = 13.8 K mol'1 and (9 = -12.8 K. The Curie constant is in good
agreement with the expected spin-only value (13.875 emu K mol") for three S
= 5/2 MnII and two low-spin S = 1/2 Fe 111 centers (Figure 4.14). The sign of
the Weiss constant indicates local antiferromagnetic interactions as expected

for F em-CN-MnII spin bridges for which there is direct overlap of the tzg
magnetic orbitals. Below 50 K, Zm deviates from the Curie-Weiss behavior

and undergoes an abrupt increase at ~11K which suggests the onset of
magnetic ordering. This state corresponds to a ferromagnetic ordering, since
the F em and Mn" spin centers interact antiferromagnetically with non-
cancellation of spins. As Figure 4.14 shows, the magnetization increases
gradually, but saturation is incomplete at 7 T (M = 11.6 1.13 versus the
theoretical value 13 pg). This behavior is a signature of a complicated
magnetic structure (competing magnetic interactions with possibly some
degree of spin canting), which is not unexpected in view of the crystal
structure. No hysteresis was observed in the field dependence of the
magnetization. Susceptibility measurements of the ac type confirm the
ferromagnetic ordering at 11 K (Figure 4.15) and reveal no significant

frequency dependence.

252

 

 

 

  

 

 

 

 

 

    

 

 

 

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Figure 4.14. Thermal dependence below 30 K of Zm at 100 G for complex

(36). Inset: temperature dependence of 1/,1’m between 2-300 K.
The solid line indicates the best fit to the Curie-Weiss law. Field
dependence of the magnetization at 2 K (bottom)

253

3.2

2.8

2.4

1.6

1.2

x' (emu/mol)

0.8

0.4

 

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1 1 L 2 1 L . {'..—.-.... 0
a 10 12
T00

Figure 4.15. Temperature dependence of the ac suceptibility (in-phase, Z,

and out-of-phase, ,1") below 13 K (ac measuring field 1 G (10'4
T); frequency of 1 Hz; no external dc field).

254

4. SUMMARY AND CONCLUSIONS

Reactions between protected metal precursors and hexacyanometallate
anions lead to interesting motifs and magnetic properties as judged by the
results presented in this chapter. Only one discrete magnetic cluster was
synthesized, namely the pentamer [Ni(2,2'-bpy)2(OH2)][Ni(2,2'-
bpy)2] [F e(CN)6]2 (38) which has an interesting, low symmetry structure.
Future work in this area will involve other hexacyanometallate anions as well
as cations with different protecting groups including tetradentate ligands
instead of two cis bidentate ligands. The possibilities are numerous and the
field will undoubtedly grow as more researchers opt to use the cyanide ligand

to construct new magnetic molecules and materials.

255

5. REFERENCES

1. (a) Keggin, J. F.; Miles, F. D. Nature 1936, I37, 577. (b) Holtzman, H.
Ind. Eng. Chem. 1945, 37, 855. (c) El-Sayed, M. F. A.; Sheline, R. K. J.
Inorg. Nucl. Chem. 1958, 6, 187. (d) Dows, D. A.; Haim, A.; Wilmarth, W.
K. J. Inorg. Nucl. Chem, 1961, 21, 33. (e) Griffith, W. P. Q. Rev., 1962, I6,
188. (f) Shriver, D. F. Structure Bonding, 1966, 32. (g) Chadwick, B. M.;
Sharpe, A. G. In Advances in Inorganic Chemistry and Radiochemistry
1966, 8, 83. (h) Britton, D. In Perspectives in Structural Chemistry 1967, I,
109. (i) Ludi, A.; Gudel, H. U. Structure Bonding, 1973, 14, l. (i) Sharpe, A.
G. The Chemistry of Cyano Complexes of the Transition Metals, Academic
Press Inc. New York 1976. (k) Dunbar, K. R.; Heintz, R. A. Progress in
Inorg. Chem. 1997, 45, 283. (l) Vahrenkamp, H.; Geiss, A.; Richardson, G.
N. J. Chem. Soc. Dalton, 1997, 20, 3643.

2. (a) Gadet, V.; Mallah, T.; Castro, 1.; Berdaguer, M. J. Am. Chem. Soc.
1992, 114, 9213. (b) Verdaguer, M. Science 1996, 272, 698, and references
therein. (c) Bushmann, W. B.; Paulson, S. C.; Wynn, C. M.; Girtu, M. A.;
Epstein, A. J.; White, H. S.; Miller, J. S. Chem. Mat. 1998, 10, 1386. (d)
Ferlay, S.; Mallah, T.; Ouachés, R.; Veillet, R.; Verdaguer, M. Inorg. Chem.

1999, 38, 229. (e) Miller, J. S.; Epstein, A. J.; Chem. Commun. 1998, 1319.

256

(f) Zhang, J.; Liable-Sands, L. M.; Rheingold, A. L.; Del Sesto, R. B.;
Gordon, D. C.; Burkhart, B. M.; Miller, J. S. Chem. Commun. 1998, 1385.
(g) Zhang, J .; Ensling, J .; Ksenofontov, V.; Gfitlich, P.; Epstein, A. J .; Miller,
J. S. Angew. Chem. Int. Ed. 1998, 37, 637. (h) Klenze, R.; Kanellakoupuolos,
B.; Trageser, G.; Eysel, H. H. J.Chem. Phys, 1980, 72(11), 5819 (i) Holmes,
S. M.; Girolami, G. S. J. Am. Chem. Soc. 1999, 121, 5593. (i) Hatlevik, 0.;
Buschmann, W. B.; Zhang, J.; Manson, J. L.; Miller, J. S. Adv. Mater. 1999,
11,914. (k) Dujardin, B.; Ferlay, S.; Phan, X.; Desplances, C.; d. Moulin, C.
C.; Sainctavit, P.; Baudelet, F.; Dartyge, B.; Veillet, P., Verdaguer, M. J. Am.
Chem. Soc. 1998, 120, 11347. (I) Ferlay, S.; Mallah, T.; Ouahes, R.; Veillet, P.;
Verdaguer, M. Nature (London), 1995, 378,701. (m) Mallah, T.; Thiébaut, S.;
Verdaguer, M.; Veillet, P. Science 1993, 262, 1554. (n) Entley, W. R.;
Girolami, G. S. Science 1995, 268, 397. (o) Babel, D. Comments Inorg.
Chem. 1986, 5(6), 285., Greibler, W. D.; Babel, D. Z Naturforsch. 1982,
87b, 832. (p) Entley, W. R.; Girolami, G. S. Inorg. Chem. 1994, 33, 5165. (q)
Juszczyk, S.; Johansson, C.; Hanson, M.; Ratuszna, A.; Malecki, G. J. Phys. :
Condens. Matter 1994, 6, 5697.

3. (a) Langenberg, K. V.; Batten, S. R.; Berry, K. J.; Hockless, D. C. R.;

Moubaraki, B.; Murray, K. S. Inorg. Chem. 1997, 36, 5006. (b) Marvilliers,

257

A.; Pei, Y.; Boquera, J. C.; Vostrikova, K. E.; Paulsen, C.; Riviere, B.;
Audiere, J .-P.; Mallah, T. Chem. Commun. 1999, 1951. (c) Vostrikova, K.
B.; Luneau, D.; Wemsdorfer, W.; Rey, P.; Verdaguer, M. J. Am. Chem. Soc.
2000, I22, 718. (d) Salah, M.; Fallah, B.; Rentschler, B.; Caneschi, A.;
Sessoli, R.; Gatteschi, D. Angew. Chem. Int. Ed. Engl. 1996, 35, 1947. (e)
Ferlay, S.; Mallah, T.; Vaissermann, J .; Bartolome, F .; Veillet, P.; Verdaguer,
M. Chem. Commun. 1996, 2481. (f) Re, N.; Gallo, E.; Floriani, C.;
Miyasaka, H.; Matsumoto, N. Inorg. Chem. 1996, 35, 6004. (g) Colacio, B.;
Dominguez-Vera, J. M.; Ghazi, M.; Kivekas, R.; Lloret, F.; Moreno, J. M.;
Stoeckli—Evans, H. chem. Commun. 1999, 987. (h) Miyasaka, H.; Ieda, H.;
Matsumoto, N.; Re, N.; Crescenzi, R.; Floriani, C. Inorg. Chem. 1998, 37,
255. (i) Kou, H.-Z.; Bu, W.-M.; Liao, D.-L., Jiang, Z.-H., Yan, S.-P.; Fan,
Y.-G.; Wang, G.-L. J. Chem. Soc., Dalton Trans. 1998, 4161. (i) Marvilliers,
A.; Parsons, S.; Riviere, B.; Audiere, J .-P.; Mallah, T. Chem. Commun. 1999,
2217.

4. (a) Ohba, M.; Okawa, H. Coord. Chem. Rev. 2000, I98, 313. (b)
Miyasaka, H.; Okawa, H.; Miyazaki, A.; Enoki, T. Inorg. Chem. 1998, 37,
4878. (c) Fukita, N.; Ohba, M.; Okawa, H.; Matsuda, K.; Iwamura, H. Inorg.
Chem. 1998, 37, 842. (d) Ohba, M.; Okawa, H.; Fukita, N.; Hashimoto, Y. J.

Am. Chem. Soc. 1997, 119, 1011. (e) Ohba, M.; Okawa, H.; Ito, T.; Ohto, A.

258

J. Chem. Soc., Chem. Commun. 1995, 1545.

5. Ohba, M.; Maruono, N.; Okawa, H.; Enoki, T.; Latour, J.-M. J. Am.
Chem. Soc. 1994, 116, 11566.

6. Ohba, M.; Usuki, N.; Fukita, N.; Okawa, H. Angew. Chem. Int. Ed.Engl.
1999, 38, 1795.

7. [Mn(2,2-bpym)2(H20)2](SO4) was synthesized by an adaptation of the
procedure reported for the perchlorate salt: Hong, D. M.; Wei, H. H.; Gan, L.
L.; Lee, G. H.; Wang, Y. Polyhedron 1996, 15, 2335.

8. Ohno, T.; Kato, S. Bull. Chem. Soc. Jpn 1974, 4 7(12), 2953.

9. SAINT 1000 and 6.0, Bruker Analytical X-ray Instruments, Madison, WI,
53719 (1999 and 2000)

10. Sheldrick, G. M. “SADABS, Siemens Area Detector Absorption
Correction”, Univ. of Gottingen, Gottingen, Germany (1998).

11. Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.; Giacovazza,
C.; Guagliardi, A.; Molitemi, A. G. G.; Polidori.G.; Spagna, R J. Appl.
Crystallogr. 1999, 32, 115.

12. Sheldrick, G. M. SHELXTL version 5.10, Reference Manuel, Bruker
Industrial Automation, Analytical Instrument, Madison, WI 53719 (1999).
Program for Refinement of Crystal Structure, University of Gottingen,

Gottingen, Germany.

259