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LIBRARY
Michigan State
University

 

 

 

This is to certify that the
thesis entitled

SYNTHESIS OF GROUP 4 METAL p-DIKETIMINE COMPLEXES

presented by

William J. Scanlon IV

has been accepted towards fulfillment
of the requirements for

Masters Chemistry

degreein

w

Major professor

DatelglfilL

0-7639 MS U is an Affirmative Action/Equal Opportunity Institution

 

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I!” m“

 

SYNTHESIS OF GROUP 4 METAL B-DIKETIMINE COMPLEXES

By

William J. Scanlon IV

A THESIS
Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE

Department of Chemistry

1998

 

ABSTRACT

SYNTHESIS OF GROUP 4 METAL B-DIKETIMINE COMPLEXES
By

William J. Scanlon IV

Controlling stereochemistry in synthesis is important in many industries. Efficient
methods of separating readily available racemic modifications into their respective
enantiomers are in high demand. This thesis chronicles initial syntheses of a family of
group 4 transition metal compounds stabilized by B-diketimine ligands, which are
precursors to catalysts for use in kinetic resolution via polymerization.

Reaction of TTPH (TTP = 2-p—tolylamino-4-p-tolylirnino-Z-pentene) with
M(NMe2)4 (M = Zr, Ti) affords (TI‘P)M(NMe2)3 and (TTP)ZZr(NMez)2. (TTP)Zr(NMe2)3
reacts further with p-toluidine to form the imine (T'I‘P)Zr(=NC6H4CH3)(NMe2) (1H
NMR). TTPH reacts with Zr(CH2C6H6)4 to give ('ITP)Zr(CH2Ph)3, which undergoes
ortho-metallation with elimination of toluene via direct o-bond metathesis to form (113—
MeC(NC7H6)CHC(N—p—Tol)Me)Zr(n2—CH2Ph)( nl—CHzPh) ((TTP*)Zr(CH2Ph)2).
DDPH(HC1) (DDPH = 2-(2,6—diisopropyl)phenylamino-4-(2,6-diisopropyl)phenylimino—
2-pentene) reacts with Zr(NMe2)4 to yield (DDP)ZrC1(NMe2)2.

Metathesis reactions of Li(TTP) and Li(DDP) with group 4 tetrachlorides produce
LMC13 (L = TTP, DD? and M = Zr, Ti,) and L2MC12 (L = TTP, M = Zr).

All compounds were characterized using 1H and l3C-NMR and in many cases

single crystal x-ray studies and elemental analysis.

 

 

 

 

 

 

To my old friend, Herschel Schmoykel Krustofsky

iii

 

 

 

 

ACKNOWLEDGEMENTS

First, I would like to thank Dr. Mitch Smith 111 for his sometimes sarcastic, often
humorous and always honest and helpful insight and guidance.

Second, I’d like thank Carl Iverson, Dean Lantero, Baixin Qian and the rest of the
Smith group, whose assistance in my Graduate School experience was priceless.

Lastly, I’d like to thank Pete LeBaron, Paul Szalay and Randy Hicks for countless

hours of pointless pontification and intellectually insulting conversations.

 

 

 

 

 

TABLE OF CONTENTS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TABLE OF CONTENTS V
LIST OF TABLES VII
LIST OF FIGURES VIII
LIST OF ABBREVIATIONS X
CHAPTER 1 1
INTRODUCTION 1
METHODS OF ASYMMETRIC SYNTHESIS l

A WORD ON POLYMERS AND THE IMPORTANCE OF STEREOCHEMICAL CONTROL ....................................... 6
OLEFIN POLYMERIZATION CATALYSTS SUPPORTED BY CYCDOPENTADIENYI I lawns 8
OLEFIN POLYMERIZATION CATALYSTS SUPPORTED BY NITROGEN CONTAINING LIGANDS ........................ 10
a_ An... .~.. M 10

f3 ,., ‘. . 12

f‘ ‘ ' ' ' (Mpg/1n) 14
ninminoe 15

‘ 'J' 16
bis(bo: ' ' ,‘ I7
APPLICATION OF B—DIKETIMINES TO ASYMMETRIC SYNTHESIS 18
CHAPTER 2 23
RESULTS AND DISCUSSION 23
LIGAND SYNTHESIS 23
SYNTHESIS OF LMX3 AND [,2sz TYPE COMPOUNDS VIA LITHIUM SALT MFTATHPQIQ 25
SYNTHESIS OF LMX; AND LZMXZ TYPE COMPOUNDS VIA ACID/BASE ROUTES ........................................ 35
FURTHER ACID/BASE CHEMISTRY 53
CONCLUSIONS 55
CHAPTER 3 ‘7
EXPERIMENTAL METHODS ‘7
INSTRUMENTAL PROCEDURES 57
SINGLE CRYSTAL X-RAY STRUCTURE DETERMINATION 57
SYNTHESES 59
APPENDIX A: BOND LENGTHS AND ANGLES 68

 

 

 

 

APPENDIX B: SINGLE CRYSTAL X-RAY STRUCTURE KEY DATA
COLLECTION AND REFINEMENT PARAMETERS 74

REFERENCES 79

vi

 

 

 

 

LIST OF TABLES

Table 1 IH NMR Data for (TTP)ZZrClz, ('ITP)TiCl3, and Li(TTP) .................................. 27
Table 2 1H NMR Data for (DDP)ZrCl3, (DDP)ZrC13(TI-IF), (DDP)TiCl3, and Li(DDP). 31
Table 3 1H NMR Data for (TTP)Zr(CH2Ph)3, (TTP*)Zr(CH2Ph)2, and TTPH ................ 38
Table 4 1H NMR Data for (TTP)Zr(NMe2)3, (TTP)Ti(NMe2)3 and (TTP)22r(NMe2)2 44

Table 5 1H NMR Data for (TP)ZZr(NMe2)2, (DDP)ZIC1(NMez)2 and

 

 

 

 

 

 

(TI‘P)Zr(NMez)(NC6H4CH3) 50
Table 6 Selected Bond Lengths and Angles for 3,4 and 5 69
Table 7 Selected Bond Lengths and Angles for 8 and 9 70
Table 8 Selected Bond Lengths and Angles for 10 and 11 71
Table 9 Selected Bond Lengths and Angles for 13 72
Table 10 Selected Bond Lengths and Angles for 14 73
Table 11 Key X-ray Parameters, Refinement and Results for 3, 4 and 5 .......................... 75
Table 12 Key X-ray Parameters, Refinement and Results for 8 and 9 .............................. 76
Table 13 Key X-ray Parameters, Refinement and Results for 10, 11 and 13 .................... 77

Table 14 Key X-ray Parameters, Refinement and Results for 14 ...................................... 78

 

 

LIST OF FIGURES

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure l (a) Kinetic Resolution and (b) Enantioselection 2
Figure 2 PLE 'meso’ Trick (bottom) and Kinetic Resolution Via Hydrolysis (top) ............ 3
Figure 3 (a) (salen)MCl (b) Olefin Approach 4
Figure 4 Jacobsen Mechanism 5
Figure 5 Tacticity in Polypropylene (a) Possible Configurations (b) Atactic (c) Isotactic
(d) Syndinmmin 7
Figure 6 Examples of Cp Alternatives 10
Figure 7 Brookhart Polymerization Mechanism 12
Figure 8 Lappert Ligand Ppraratinn 13
Figure 9 cis-Out of Plane Structure 14
Figure 10 Polylactides 18
Figure 11 Kinetic Resolution of Polylactides Via Polymerization ................................... 19
Figure 12 General Ligand Synthesis 21
Figure 13 Synthesizing Diastereomers vs. Enantiomers 22
Figure 14 Scheme for Synthesis of 7b 24
Figure 15 Bailar Twist Mechanism 26
Figure 16 ORTEP Diagram of (TTP)ZZrC|; 28
Figure 17 Cationic Mechanism of Ring Opening Polymerization .................................... 29
Figure 18 ORTEP Diagram of (TTP)TiC13 33
Figure 19 ORTEP Diagram of (DDP)ZIC13 34

 

viii

   

 

 

 

Figure 20 Acid / Base Routes

Figure 21 Possible Thermolysis Mechanisms of (TTP*)Zr(CH2Ph)2 ...............................

Figure 22 ORTEP Diagram of (TTP)Zr(CH2Ph)3

 

Figure 23 ORTEP Diagram of the Thermolysis Product

Figure 24 Thermolysis of BenTiMez to (TwistBen)Ti

 

 

Figure 25 ORTEP Diagram of (TTP)Zr(NMe2)a

 

 

Figure 26 ORTEP Diagram of ('ITP)Ti(NMe2\3

Figure 27 Transamination to fOITn DTPH

 

Figure 28 ORTEP Diagram of (TP)ZZr(NMe2)2

 

 

Figure 29 ORTEP Diagram of (DDP)ZrCl(NMez)g

 

Figure 30 Aminolysis to Form an Imine
Figure 31 Alcoholysis of LM(NMe2)3 and L2M(NMe2)2

Figure 32 Proposed Aminolysis Reaction

 

 

 

Figure 33 Other Possible Reactivity

35

37

39

40

41

45

46

47

51

52

53

54

55

56

 

 

 

 

 

TPH

TTPH
(TTP*)Zr(CH2Ph)2
TMPH

DPH

DPPH
DTPH

LIST OF ABBREVIATIONS

4-p-toluidinO-pent-3-en-2-one
2-p-tolylamino-4-p—tolyliminO-2-pentene
(n3—MeC(NC7I-16)CHC(N—p—Tol)Me)Zr(nz—CHZPhX nl—CHzPh)
4-(2,4,6-trimethyl-anilino)-pent-3-en-2-one
4-(2,6-diisopropyl-anilino)-pent-3-en-2-one
2-(2,6-diisupic,.,1,2.-.”‘ ' )4 (2,6-diisopropylphenylimino)-2-
pentene

2-(dimethylaminO-4—(4-tolylimino)-2-pentene

 

 

 

 

 

 

 

 

 

 

 

 

CHAPTER 1

INTRODUCTION

Methods of Asymmetric Synthesis

Obtaining optically pure reaction products (asymmetric synthesis) is often
paramount in fully realizing a compound’s practical utility. For example, pharmaceutical
compounds commonly have one active enantiomer and another that is inert, deactivating,
or even toxic.l As a result, enantiospecific synthesis has evolved into an important
synthetic discipline.

There are basically two methods used to synthesize chiral molecules: kinetic
resolution and enantioselective synthesis from prochiral substrates (Figure 1). In kinetic
resolution, a chiral auxiliary is added to a racemic modification. The auxiliary selectively
reacts with one enantiomer leaving the other behind. This method is convenient because
racemic modifications are readily available. The inherent downside to kinetic resolution
is consumption of half of the starting material (ie., maximum yield is 50%). Direct
enantioselective synthesis does not have this problem. This method relies on interaction
between a chiral auxiliary and a prochiral substrate to produce only one enantiomer. In
this way, all of the Starting material (in theory) can be converted to chiral product. This
approach requires that functionality be introduced with high regio and stereoselectivity,

whereas the desired funtional group is already in place in kinetic resolution schemes.

 

 

 

Prochiral

 

A(R) :‘ A
(

+
A(S) Auxiliary (S) R) Auxiliary (R) Substrate
(a) (b)

Figure l (3) Kinetic Resolution and (b) Enantioselection

Both of these methods can proceed stoichiometrically or catalytically. Catalytic
reactions have one large advantage over using stoichiometric reagents, namely
stoichiometric amounts of chiral auxiliary are not required. For these reasons and Others,
asymmetric catalysis has received considerable attention in recent years.“

Nature employs catalysts (such as enzymes or entire cells) that perform
asymmetric catalysis with a sublime mastery. These biocatalysts have been
“domesticated” by chemists and used for synthetic processes.2 For instance, pig liver
esterase (PLE) is an enzyme that hydrolyzes the various of esters ingested by pigs. It is
the most widely used esterase in enzymatic asymmetric synthesis, because it accepts such
a wide range of substrates. PLE is usually utilized in enantioselective synthesis via the
‘meso trick’. As exemplified in Figure 2 (bottom), PLE selectively hydrolyzes one of the
esters in a meso diester compound.5 The resulting chiral compound is recovered in high
yield and high enantiomeric purity. Using PLE, this approach has been extended to
kinetic resolution. In Figure 2 (top), PLE is added to a racemic modification of chiral
esters.6 It selectively hydrolyzes one of the enantiomers, which can be recovered in high

yield and high enantiomeric excess. The high yields and excellent enantiomeric excesses

 

 

 

 

 

 

 

 

enhance the appeal of PLE catalysis, but syntheses that exploit these systems are

sometimes limited.

C02Et H020 002Et
/ PLE \ + /
——->
0.2M
o o o

MeCN
(+/_) 40% yield 48% yield
96% ee 83% ee
A\\C02Me PLE ‘\\\002Me
0 #

II/COZMe ”’002H
99% yield
>98% ee

Figure 2 PLE 'meso' Trick (bottom) and Kinetic Resolution Via Hydrolysis (top)

In recent years, inorganic systems have begun to rival biological ones in their
utility. Noteworthy advantages of inorganic metal asymmetric catalysts over biological
catalysts are as follows: (i) metals can perform reactions natural systems will not; (ii)
chiral metal catalysts can be easily alterable through ligand modifications; (iii) metal
catalysts can be designed to withstand non-biological environments; and (iv) metal

catalysts can accept a wider variety of substrates than biocatalysts.7

 

 

 

 

 

 

 

 

R" Fl"
0
_N\"/N_ H nun
/M\ O
'R O C. 0 Ft' —N u,”—
M".
R R 0 CI 0

(a) (b)

Figure 3 (a) (salen)MCl (b) Olefin Approach

Jacobsen has recently reported enantioselective epoxidation of cis-Olefins8 and
kinetic resolution of terminal epoxides via catalytic hydrolysis,9 using metal complexes.
In the case of enantioselective epoxidation, changes in the enantiomeric excesses with
variations of the R, R’ and R” groups were Observed (Figure 3(a)). The highest
enantioselectivity was Obtained when the steric properties were adjusted such that olefin
interaction with the dissymmetric portion of the ligand was maximized (Figure 3(b)).
These results demonstrate the importance Of controlling the steric properties of an
asymmetric catalyst. The simple reaction mechanism shown in Figure 4 was proposed for
epoxidation. It suggests that addition of an alkene (ex. cis-olefin substrate) to the 0x0
moiety generates a radical intermediate. In this intermediate, the alkyl group can collapse

(forming the cis isomer) or rotate and collapse (forming the trans isomer).

 

 

 

 

 

 

 

 

Ls.
<2I:> <:i°~:>\ 9

Figure 4 Jacobsen Mechanism

Jacobsen also demonstrated the dramatic effects of catalyst electronics on
asymmetric synthesis (at least in the case of epoxidation).lo By varying the R’ group from
electron donating (ie., R’ = OCH3) to electron withdrawing (ie., R’ = N02), a change in
the enantioselectivity of the catalyst was observed. The electron donating groups were
found to increase the enantioselectivity. The proposed explanation presumes that the
high-valent (salen)Mn(IV)O-olefin intermediate influences the stereochemistry Of the
epoxide in accord with the Hammond postulate in the following way. The electron
donating groups stabilize the intermediate, making it a milder oxidant so that the oxygen
to alkene transfer proceeds via a more product-like transition state. At the origin of the
reaction coordinate, the reactants do not interact at all. Therefore, a higher degree of
stereochemical communication might be expected in the later transition state. The
electron withdrawing substituents are expected to destabilize the intermediate, making it a
more reactive oxidant. Here a more reactant like transition state might be expected with
poorer stereochemical communication.

This example emphasizes the importance of being able to control the electronic

and steric properties of a catalyst. Transition metal compounds have long been used to

 

 

 

 

 

 

 

 

 

 

 

 

 

 

catalyze several types of reactions including POIymerizations and organic syntheses such

as hydroforrnylations, hydrogenations, hydrocyanations and hydroborations.” In recent
years, they have become important tools in asymmetric syntheses. Their ability to
accommodate various ancillary ligand sets makes them ideal to obtain the electronic and

steric tuning requirements necessary to design efficient enantioselective catalysts.

A Word on Polymers and the Importance of Stereochemical Control

The importance of polymers is evident in almost every facet of daily life. For
example, polypeptides are important natural polymers composed by linking together
many amino acids. They are present in enzymes, and fill many other important roles in
natural biochemistry. DNA is another example of a very important natural polymer.
Natural polymers such as wool and silk, which are also polypeptides, have been used for
thousands Of years.

In the twentieth century, chemists have developed numerous methods to
synthesize unnatural polymers. These polymers are used in more wide and varied
applications than any other class Of chemical. Polymers are employed as fibers, plastics,
or elastomers. Fibrous polymers are strong, deformation resistant substances used in the
manufacture of clothing and ropes. Plastic polymers are classified as rigid plastics and
flexible plastics. Rigid plastics are hard, non-flexible materials that find applications
ranging from appliance housings to hardhats. Flexible plastics, conversely, are softer,
much more pliable substances. They find use as packaging films. Elastomers are
extremely flexible polymers that return to their original shape and size after being

stretched a great deal.12

 

 

 

 

 

 

 

 

 

The properties (hardness, flexibility, melting points, elasticity, etc.) of polymers

depend on several variables including the identity of the monomers, the molecular mass
of the polymer and the amount of branching in the polymer. Some monomers contain
stereocenters or have the potential to form stereocenters upon polymerization. In such

cases, orientation of relative stereocenters can have a marked effect on the properties of

 

    

 

   
   

 

the polymer.
viii IT?
‘ | l l l I l l
; :1 CH3H CH3H H H CH3
H H H Fl (D)
SAME SIDE
H H H H H H H
l L | I l | |
l l | I l I 1
CH3 H CH3 H CH3 H CH3
H30? H 9H3 (c)
.__ H H CHaH H H CH3
H n H 1;. l l | l l | |
OPPOSITE SIDE dual: III I—li (IDHSIL Ili
(a) (d)

Figure 5 Tacticity in Polypropylene (a) Possible Configurations (b) Atactic (c)
Isotactic (d) Syndiotactic

Polypropylene is one of the simplest examples Of a prochiral monomer. During
polymerization, the methyl group can adopt syn or anti configurations with respect to the
previous stereocenter (Figure 5(a)). The stereoregularity is termed tacticity. Three
different tacticities are possible. In the first situation, the configurations of the
stereocenters are distributed randomly (Figure 5(b)). The polymer is then said to be
atactic. In the second case, consecutive stereocenters have identical configurations (ie. R

groups are on the same side (Figure 5(c))). These polymers are termed isotactic. In the

 

last case, polymers have consecutive Stereocenters with repetitive alternating

configurations (ie. each R group is opposite of the previous (and subsequent)(Figure
5(d))) and a syndiotactic polymer results.

Atactic polymers have difficulty in packing efficiently into a crystal lattice,
because of their irregular configurations. As a result, they tend to be amorphous
(noncrystalline), soft (‘tacky’) substances with little or no physical strength. Atactic
polymers find few applications in industry. On the other hand, isotactic and syndiotactic
polymers tend to pack well in crystal lattices, because their regular structures allow for
closer interaction of the polymer chains. The resulting polymers are highly crystalline
substances that are physically robust and display good resistance to solvents and

chemicals. Isotactic and syndiotactic polymers have wide-ranging industrial applications.

Olefin Polymerization Catalysts Supported by Cyclopentadienyl Ligands
Ziegler-Natta catalysts (generally consisting of a Group 3-8 transition metal with a
Group 1, 2 or 13 organometallic) have been very successful in facilitating low
temperature—low pressure polymerizations. Some early, Ziegler-Natta catalysts gave
stereoregular polymers. For example, Natta found that the polymerization of propylene
using TiCl4/Et2AlCl gave a highly isotactic polymer.13 These early Ziegler-Nana catalysts
were heterogeneous. In such systems, the control of the polymer stereochemistry is
derived from the chirality of the crystal lattice.12 Active sites are thought to be located at
defects on the crystal surface. Modifying the chirality of the crystal or adjusting the active
site is virtually impossible. Thus, heterogenous catalysts Offer little real control of

polymer stereochemistry.

 

 

 

‘3

 

 

Cyclopentadienyl (Cp) organometallic compounds of the type Cp2MX2 (when

activated with methylaluminoxane (MAO) or other Lewis acids ([Pth][B(C6F5)4] or
B(C6F5)3) have become extensively used as homogeneous Ziegler-Natta catalysts.
Polymerization in these Species proceeds via Olefin coordination and insertion of a
cationic transition metal species.” The cation is generated in situ when MAO is used as a
cocatalyst. [szMR+][BAr4‘], however, can be synthesized upon reaction of szMRz with
[Pth][B(C6F5)4] or B(C6F5)3 and then used in polymerization. Either way, the formation
of a cationic species appears to be important to catalytic activity.”

Some of these homogeneous systems have shown stereoselectivity. The
(Cp)2Ti(Ph)2 / MAO system, for example, produces isotactic polypropylene.l6 This
system is unusual, as most stereoselective catalysts are chiral molecules, such as racemic
1,1’-ethylenedi—115-indenylzirconiurn dichloride.” Whereas polymer configuration in
heterogenous catalysis depends on the chirality of the crystal lattice, the chirality of the
molecule of the transition metal compound dictates configuration in homogeneous
catalysis.

The effects Of steric and electronic modification of Cp rings on Olefin
polymerization has been reviewed.18 The wide range of polymerization conditions and a
lack of quantitative evaluations has hampered drawing definitive conclusions. However,
some general themes are apparent. In (CpR)2MC12 catalysts, electronic effect Of R on
polymerization activity dominate over steric effects. The electron withdrawing groups
enhance catalytic activity, presumably by increasing electrophilicity of the metal,
resulting in more facile olefin coordination and insertion. Steric effects play a minor role

in polymerization activity unless R or the Olefin are rather large and the metal is small (Ti

 

 

 

 

 

 

 

vs. Zr). Steric considerations are thought to be more important in controlling the tacticity

of the polymer.

Olefin Polymerization Catalysts Supported by Nitrogen Containing Ligands

Modification of Cp ligands is not trivial. For that reason, as well as the plethora of
patents on Cp systems, investigation into non-Cp Ziegler-Natta catalysts has intensified.
In the following section, some examples of ligands systems currently under consideration
are discussed. All of the systems mentioned have the advantage of easily adjustable
electronic and steric properties. It should also be noted that in cases where polymerization
is observed, activities are usually far lower than that of metallocenes.

d

r
j i l N N
R R N N
(a) “9 Q
(C)
R R
R\NH HN/R R—N HN—FI \B B/
\Y R/ \NH HN’ \R
R. \_/

(d) (e) (0
Figure 6 Examples of Cp Alternatives
a-diimines
There are late transition metal catalysts supported by a-diimines ligands (Figure
6(a) L‘”), which are active for olefin polymerization.”21 In the most significant instances,

Brookhart has successfully polymerized ethylene and other OI-olefins to high molecular

 

 

 

 

 

 

 

I III-
III .uflufll

 

weights (at 14 atm and 0-25 °C) with [(AYN=C(R)C(R)=NAr)M(CH3)(OEt2)} [B(3,5—

C6H3(CF3)2)4] (M=Pd or Ni, Ar = 2,6—diisopropyl benzene, R = Me or H).20 Using a
similar system, the first copolymerization of ethylene and propylene with polar-
functionalized vinyl monomers to high molecular weight was also reported.” These
results are improvements over most late metal Ziegler-Natta type catalysts which tend to
dimerize or oligomerize Olefins due to B-hydride elimination.22 Brookhart found that
reducing the steric bulk of the ligand by replacing the 2,6-diisopropyl benzene with 2,6-
dimethylbenzene resulted in less branched, more linear polymer with a decreased
molecular weight. The mechanism proposed in Figure 7 was based on exhaustive NMR
studies. The rate of exchange of bound ethylene on L‘a’Pd(Me)(OEt2) with free ethylene is
dependent on ethylene concentration. Ethylene displacement of the Ot-olefin in formation
of D in Figure 7 was therefore assumed to be a dissociative mechanism requiring
coordination of the ethylene to an axial position on the metal. The ortho substituents on
the aryl groups are arranged as to interfere sterically with such an approach. As a result,
when the ortho substituents are large, the chain termination transition state is disfavored
and longer polymer chains (ie., higher molecular mass polymers) are produced.
Brookhart’s system nicely demonstrates the importance that even small changes of ligand

steric properties can have on catalyst reactivity.

 

<N\M’CHZCHEI:I; N‘MH = CN‘MNR gspl. “I‘M/u.
N’ WI N’ N, \H T N, \H
(A) Om) (C) /‘R (D)
. , ll. , l
(N) CHL——__ CN:M)\CH3 CN‘M’H
~ \ll ~ ~’ \I
(E) l (G)
chain chain
migration growth

Figure 7 Brookhart Polymerization Mechanism

fl-diketimine

Similar to Ot-diimines, B-diketimine (or bis(ketenimine)) (Figure 6(b) U“) ligands
are prepared by reaction of B-diketones with primary amines.23 Most usage of B-
diketimines has been with late transition metals."”'23'24 There are examples of B-
diketimine main group compounds.”26 Surprisingly, little work has been carried out with
early transition metals.”'29 Lappert synthesized L(b)*MC13 (L‘b)* =
tBuC(NR)CHC(NR)Ph, R = SiMe3, M = Zr, Ht)(1) in 1994.27 It is interesting to note that
the ligand synthesis for this compound is not the usual condensation of primary amines
and a B-diketone. Lappert found that reaction of LiCH(SiMe3)2 with tBuCN results in the
formation of [C(SiMe3)HC(‘Bu)CN(SiMe3)Li]2 (Figure 8). Adding two equivalents of
PhCN to this complex results in the formation of [L(b)*Li]2 which was then reacted with

ZrC14 to give L‘b"ZrC13.

 

tBu

 

 

Me Si S'M . _ .
t 3 \ A I 63 \ /LJ\ /S|Me
LiCH(SiMe3)2 BUG” T ll 2PhCN MeaSI N N
. \/N
t
Bu

Figure 8 Lappert Ligand Preparation

It was only recently that Collins prepared several B-diketimine compounds of the
type L(b)ZrX3 and (L‘b))ZZrX2 (Ar = phenyl, R = methyl in Figure 6(b)).28 Alkane
elimination reactions were used to prepare L‘b)Zr(CH2Ph)3 from Zr(CH2Ph)4 and L‘wH.
Amine elimination reactions involving addition of one or two equivalents of LmH to
Zr(NMe2)4 were used to synthesize L‘b)Zr(NMe2)3 and (L‘b))ZZr(NMe2)2 respectively. L‘b)’
Zr(NMe2)3 (Ar = p—CF3C6I-14 in Figure 6(b)) was prepared by the same methods.
(L‘b)’)ZZr(NMe2)2 was not thermally stable and could not be isolated in pure form. Chloro
derivatives (L‘b)ZrC13, L(b”ZrCl3, and (I.(b))ZZrClz) were prepared by reaction of the
dimethylanrido compounds with MezNH(HCl) or Me3SiCl.

Collins was able to alkylate the chloro derivatives with MeLi or PhCHzMgCl to
give (L‘b))2Zr(CH2Ph)2 and (L‘b’)2ZrMe2. Reaction of the chloro derivatives with CpLi and
IndLi also gave L(b)ZGCClz, La’)ZrIndC12, and L(b)’ZGCC12.

After comparing X-ray structures of (L“”)22r(NMe2)2 and L‘b’ZrIndCIZ, Collins
suggested that the B-diketimine ligands can modify their mode of coordination to the
metal in response to the donor properties of the ancillary ligands. For example, in
(L‘b))ZZr(NMe2)2 with its strong rt-donor ligands, the B-diketimine ligand presumably acts

as a 20, 4e' donor to give a 16 e' compound. On the other hand, in the more electron

 

 

 

 

 

 

deficient L‘b)ZrIndC12, hapticity of the B-diketimine ligand shifts from n2 to n5 to increase

1: coordination of the ligand to the metal . The 1t-donation from the B-diketimine ligand,

however, is assumed to be weak.

 

C‘ ‘ " " ‘ ’ (Megtaa)

Megtaa (Figure 6(c)), a macrocyclic analog of B-diketimines, has been used by
Jordan30 to stabilize group 4 transition metals. This ligand is prepared via a Ni-templated
condensation of 2,4—pentanedione and 4,5-dimethyl-1,2-phenylenediamine. Salt-
elimination, alkane-elimination, and amine-elimination reactions similar to those
described previously were used to synthesize chloride, alkyl, and amide complexes of the
form (Megtaa)MX2 (X = Cl, Me, CstlMC3, CHzPh, CH2CMC3, NMez, NEtz M = Zr, Hf).

All of the resulting complexes have a cis out of plane structure (Figure 9).

 

Figure 9 cis-Out of Plane Structure

Migration of a Zr bound methyl group to an electrophilic Megtaa imine carbon
was Observed for (Megtaa)ZrMe2. This migration is accelereated by a Lewis base to yield
(lVIe9_taa)MX(base). Alkyl migrations did not occur in the bulkier zirconium analog (R =
CH28IM63) or in the analogous halfnium compounds (R = Me, CHZSiMe3). Such
migrations have been observed for the similar (Me4taa)MR2 and (Me4taen)MR2

complexes.31

 

The cationic species [(Megtaa)MR+][B(C6F5)4'], formed by protonolysis of

(Megtaa)MR2 with [HNMePh2][ B(C6F5)4] or [HNMezPhH B(C6F5)4] polymerized
ethylene poorly. Jordan proposed that the [(Megtaa)MR+][B(C6F5)4'] compounds have a
low tendency toward formation of 1: complexes with alkenes and alkynes.
Diamines

The first example of living polymerization of aliphatic Ot-Olefins at room
temperature was reported by McConville.32 The cationic alkyl complex derived by methyl
anion abstraction from the diarrrine compound [ArN(CH2)3NAr]TiMe2 (Ar = 2,6-
diisopropylbenzene, 2,6-dimethylbenzene) is the catalyst that performs this living
polymerization. The diamine ligands in this report (Figure 6(d), L‘d)) were prepared by

reaction of two equivalents of LiNHAr with Br(CH2)3Br (two equivalents of

 

tetrahedgletlu‘ " ' were necessary to prevent formation of an undesired
elimination product, ArNHCHZCH=CH2).

McConville also reported the polymerization of aliphatic Ot-olefins by
[ArN(CH2)3NAr]TiX2 (X = Cl, Me Ar = 2,6-diisopropylbenzene, 2,6—dimethylbenzene)
activated with methylaluminoxane (MAO).33 Zirconium analogs of the type L‘d)ZrX2 (X =
Cl, NMez, Me, CHzPh) have also been synthesized.34 Polymerization (as well as
production of oligomers) of l-hexene was observed when L‘d)ZrMe2 was activated with
MAO at 68 °C. Chain end analysis suggests that a cationic alkyl [L(")ZrP]+ (P = polymer)
inserts l-hexene in a 1,2 fashion (similar to the L‘d)TiMe2 system) followed by B-hydride
elimination. It appears that chain transfer to the aluminum (and not B-hydride

elimination) is the mechanism of chain termination in the titanium/MAO system, as

 

olefinic resonances have not been observed in the 13Cl IHl-NIVIR spectra of the polymer

or oligomers produced.

As opposed to L‘dTiMeZ/B(C,F5)3, which produced a living polymerization at 23
°C, L‘d)ZrMe2/B(C6F5)3 was not active for polymerization l-hexene at 23 °C. Reaction of
equimolar amounts of L(d)ZrMez and {Ph3C}[B(C6F5)4] did oligomerize l-hexene at 23

°C, but no evidence of high polymer was found.

Amidinates
Anridinate ligands (Figure 6(e) L‘”) are used frequently to prepare various types of

“'38 and lanthanide37 metals. These bidentate

complexes with main group,35 transition
ligands are four electron donors with a small chelating angle (~115°). The steric
properties are thought to lie somewhere between those of Cp and Cp"‘.37 Being “harder”
in character than Cp, amidinates should form highly polarized M-N bonds leading to a
more electrophilic metal.37’“

Eisen has reported that generation of ‘cationic’ compounds from reaction of
(L(°))2ZIC12 (R = SiMe3 and R’ = Ph or tolyl) with MAO resulted in polymer active
catalyst.38 It was Observed that smaller ratios of MAO/catalyst improved the catalytic
activity and molecular weights of the polymer. The opposite is true of early transition
metal Cp systems39 where the high amounts of MAO cocatalyst required can limit
economic viability. These increases are attributed to the role of MAO in chain
termination processes (alkyl transfer, etc.,).

Rausch has synthesized the titanium amidinate compounds L(°)'l‘i(OiPr)3,

{L‘°*riC13}2, L‘e’l‘iCl3(THF), and L‘e’I‘iC13(PMe3) (R = SiMe3 and R’ = Ph) and found

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

them to be active in the polymerization Of Styrene when activated with MAO."o The

resulting polymer was highly syndiotactic. {L(°’TiC13}2 had the highest activity followed
by L“)Ti(O’Pr)3. L(°)'1‘iCl3(THF), and L(C)TiC13(PMe3) had the lowest activities due to the
electron—donating THF and PMe3 groups which greatly deactivate the metal. (L(e))2TiC12
did not polymerize ethylene.

{L‘°’TiCl3}2, L("Ti(OiPr)3, (L(°))2TiClz and (L<“));.,ZrCl2 when activated with MAO
were found to react very slowly with ethylene at 20 °C and not at all with polyethylene
under similar conditions.

Surprisingly, (L(°))ZZrMe2 and (L(°))2TiMe2 were found to be inactive for
polymerization of ethylene or propylene when activated with Ph3C[B(C6F5)4]. However,
Arnold has isolated (L‘e’)2ZrMe[MeB(C5F5)3] from reaction of (L(‘))ZZrMe2 with
B(C6F5)3. This species was found to be moderately active toward ethylene
polymerization.“

Richeson was able to prepare an amidinate family consisting of (I_.(e))2MC12 (R =
cyclohexane, R’ = Me for M = Zr, Ti, Hf and tert-butyl for M = Zr) and (L(°))2MMe2 (R’
= Me, M = Zr).42 All compounds polymerize ethylene when activated with MAO.
Lowering the ratio of MAO/catalyst resulted in slight increase in molecular weight

similar to Eisen’s findings.

bis(borylamines)
Schrock has synthesized group 4 transition metal complexes stabilized by the
bis(borylamine) ligand [MeszBNCHZCHzNBMeszf' (Benz‘) (Figure 6(0).43 The Ben

ligand is made by reaction of HZNCHZCHZNHz with (1) 2LiBu/THF and (2) 2Mesity12BF

to yield MeszBNHCHzCHzNI-IBMesz (H2(Ben)). Schrock was able to synthesize the
dichlorides (Ben)TiC12 and (Ben)ZrClz(TI-IF). From the former, monoalkyl- and
dialkyltitanium derivatives were made ((Ben)TiRCl (R = CHzPh, CHzCMe3) and
(Ben)TiR2 (R = CHzPh, Me) by reaction with corresponding Grignard reagents. Though
(Ben)ZrMe2 was prepared analogously, it was less thermally stable than (Ben)TiR2 and
was found to undergo metallation of an ortho methyl group to form a dicyclometalated
compound. Reaction of (Ben)TiMe2 with B(C6F5)3 results in [(Ben)TiMe][MeB(C6F5)3]
which did not polymerized ethylene readily at 25 °C and [-2 arm possibly in part due to a
strong binding Of the anion to the metal. Schrock concludes that a steric increase on the
Ben ligand is required to expel the [MeB(C6F5)3]‘ in the presence of ethylene and also to

prevent the dimerization Observed in (Ben)ZrMez.

Application of fi-diketimines to Asymmetric Synthesis

0 o
\vgko Cat‘ 0 . .
OYL“ O
O n

O

 

Figure 10 Polylactides

Polylactide materials (Figure 10) are ideal for employment in a wide range of
medicinal applications from absorbable wound dressings and sutures to controlled release
drug capsules, because they are biocompatible, biorenewable, and biodegradable. As with

any polymer, controlling the properties of the polymer to best fit the desired application is

paramount.

 

 

 

 

 

 

Tin and zinc octanoates, M(02CR)2, are the most common dilactide
polymerization catalysts.“ Catalysts of this type offer little in the way of electronic or
steric adjustability. Also, they have several sites of polymer initiation leading to multiple
chain transfers and an ill-defined polymerization. A catalyst with tunable steric and
electronic properties and a Single initiation site would be more ideal.

The cyclic monomer 3,6-di(alkyl or aryl)—1,4—dioxane—2,5-dione (dilactone)
contains two chiral centers and can form a polylactide by a ring-opening polymerization
(ROP). By adjusting the electronic and steric environment of the catalyst, one might
achieve kinetic resolution via polymerization Of a racemic modification of dilactone.
Potentially, catalytically selective polymerization of one enantiomer (and the meso-
monomer (ex. R, R and RS» would leave the 8,8 monomer in solution (Figure 11). The
8.5 monomer could then be polymerized into a stereoregular polymer (8,8) or hydrolyzed

to produce the enantiomerically pure lactic acid derivatives.

H O 4 O H e O
\
6 ..)|H+ OI .uiil Y O ’z
\ H o H n
O O (8)

(3,8) (RR)
Cat*(R,R) Cat
0 0 s t H O
H,’ \H epara e ,1,
o '-"H + Y O o ....H
\ 0 H ’ n Polymer
o O
(8.3) (R) (8.8)

Figure 11 Kinetic Resolution of Polylactides Via Polymerization

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In order to encourage and sustain polymerization, a highly electrophilic metal is

desired in an asymmetric catalyst. The ligand sphere is designed to control the reactivity
of that metal. It should ultimately be composed of two parts: an active moiety and an inert
moiety. The active moiety is responsible for initiating the reaction and should be easily
dissociated from the metal. The inert moiety should be unreactive and control the activity
and stereoselectivity of the reaction. This inert moiety must have adjustable steric and
electronic properties, so it can be customized to exclusively select (or exclude) a
particular substrate.

We are interested in exploring the polymerization activity of compounds with
group 4 transition metals. Plus four (do) oxidation states yield a highly electrophilic metal.
As a consequence, they tend to form bonds that are more ionic in character. This
increased polarization causes these bonds to be innately more reactive (a beneficial
quality for ligands that might initiate polymerization (ie. active moiety».

Bis mono- and diketimines ligands are employed as the inert components because
their facile synthesis from 2,4-pentadione and primary amines facilitates tuning steric and
electronic properties by varying the amine. The alkene proton (at ~ 6 — 4 ppm) and methyl
protons (at ~ 2 ppm) also provide diagnostic lH NMR spectroscopic handles. A schematic

of the general synthesis is shown in Figure 12.

20

 

 

 

 

1 1
o O H2NR1 R‘NH o H2NR2,H"‘ R‘NH N’RZ

M 1100 M 1100 M

R:-©_ -g} 33

Figure 12 General Ligand Synthesis

Initial stages of this project involve synthesizing a family of compounds of the
type L2MX2 (Figure 13) and surveying their reactivity. Then, using different groups for R1
and R2, chiral transition metal complexes may be synthesized. These chiral complexes
could ultimately be used as asymmetric polymerization catalysts.

As racemic mixtures of these compounds may be difficult to separate, utilization
of anrino acids (Is-phenylalanine, L-cysteine, L-valine, etc) and other chiral R groups are
of interest. Figure 13 demonstrates how a chiral metal produces a pair of enantiomers,
which may be difficult to resolve. On the other hand, a chiral metal with a chiral ligand
(R = L-phenylalanine) produces diastereomers, which should be resolvable by fractional

crystallization.

21

 

 

 

 

 

 

Mirror

a) Enantiomers

Mirror
H ‘\‘.CH2Ph HOOC,,,,H
NJ‘COOH Pthc/LN/D
, l.\\x x,,,, .. -
Fr yak "Zri R
R—N l X X l

‘R
DN‘R R’NJ

b) Diastereomers

Figure 13 Synthesizing Diastereomers vs. Enantiomers

What follows are details of the syntheses and characterizations of a family of

compounds that show promise as precursors to asymmetric catalysts.

22

 

 

TN.-

 

 

Chapter 2

RESULTS AND DISCUSSION

Ligand Synthesis

Synthesis of diketirrrine 2b (Figure 14) was of interest because of the large
sterically demanding R groups. Figure 14 summarizes the results Of this effort (see
Chapter 3 for experimental details).

The syntheses proceeded well with the exception of the final step (the second
amine condensation). The large bulk of the R group probably inhibits condensation of the
second amine. Successful synthesis of other sterically demanding ligand systems (namely
R1 = R2 = mesityl or 2,6-diisopropylphenyl) suggest that this step may indeed be
achievable in good yields. Compound 2a (4-(bis 3,5-(3,5-di-tert-butylphenyl)—
phenylimino)-pent-4—en-2-one) is potentially useful as the monoimine or in combination
with a second less bulky amine (ie., p-tolyamine or alkylamines). The large R group
might be effective as a blocking group. At the very least, the preparation of compound 2a
demonstrates some of the versatility in amine synthesis that may be applied to ligand

design.

23

 

Ififl—Igl T
O O O
“M NH
O M O 0 m
“‘00 /
is)?

Figure 14 Scheme for Synthesis of 2b

24

 

 

 

 

Synthesis of LMX3 and L2MX2 Type Compounds via Lithium Salt Metathesis

Previously in our group, a family of monoketimines consisting of
('TP)2ZrC12, (TP)2TiC12 and (TMP)2TiC12 (TP = 4—p-tolylimino-pent—4—en-2-one and TIVIP
= 4-(2,4,6-trimethylphenylimino)-pent-4-en-2—one) were synthesized via metathetic
reactions and fully characterized.45 The general synthesis of LnMClx compounds was
achieved via a lithium salt metathesis method. The general scheme is shown in Eq ( 1)
(Li(L) = Li(TTP) and Li(DDP), M = Ti or Zr).

Eq (1) MC14 + nLi(L) -) (L),,MC14_n + nLiCl

The lithium salts of the B-diketimine ligands were prepared in excellent yield by
reaction of the B-diketimine free base with n-butyl lithium. The ligand lithium salt was
collected from ether as light colored precipitate (white to yellow).

Addition of two equivalents of the lithium salt of the TI‘PH ligand (Li(TTP)) to a
stirred toluene suspension of ZrC14(THF)2 resulted in the formation of (TTP)ZZrC12 (3) in
50% yield. The significant shift of the backbone alkene proton resonance from 4.67 ppm
for Li(TTP) to 5.34 ppm was indicative of metal coordination. The room temperature 1H
NMR spectrum exhibits two methyl resonances, one corresponding to the tolyl moieties
and the other corresponding to the ligand backbone (Table 1). Upon cooling (-50 °C),
four methyl signals are observed suggesting cis-chloride configuration and a C2
symmetry. An X-ray crystal structure (Figure 16 and Appendices that contain X-ray
collection parameters and bond lengths and angles) indicates a C2 symmetry with cis
arrangement of the chlorides in an octahedral metal environment. (TTP)ZZrC12 obviously

interchanges between enantiomers at room temperature. An analogous compound,

25

 

 

 

 

III .III ill .I r. I

 

 

 

 

(PPP)ZZrC12 (PPPH = 2-phenylamino-4-phenylimino-2-pentene), was prepared by Collins

via reaction of (PPP)2Zr(NMe2)2 and two equivalents of [MezNH2][Cl].28 (PPP)22rCl2
demonstrates similar spectroscopic characteristics. The Bailar twist mechanism46 (Figure
15) proposed for (PPP)zZrC12 also accounts for the observed fiuxional behavior of
('I'I'P)2ZIC12. In both cases, the enantiomers interconvert rapidly on the NMR time scale
via a trigonal prismatic intermediate in which both backbone methyls (and both tolyl

methyls respectively in the case of 3 are equivalent).
Zr —//C ~——‘NN\?CI — (Cl: Z—r/

Figure 15 Bailar Twist Mechanism

26

 

 

 

 

Table l 1H NMR Data for (TTP)2ZrClz, (T TP)TiCl3, and Li(TTP)

 

 

 

 

 

 

Compound 8 ppm Appearance Assignment
Li(TTP) 6.91 d, 4 H, J = 8.0 Hz aromatic
(CDC13) 4.01 d, 4 H, J = 8.0 Hz aromatic

4.35 s, 1 H alkene
2.25 s, 3 H CH3 wry.
1.61 s, 3 H CH3 backbone
('I'I‘P)ZZrC12 7.01 d, 4 H J = 8.1 Hz aromatic
(CDClg) 6.71 br s, 4 H aromatic
5.34 s, 1 H alkene
2.28 s, 6 H CH3 tolyl
1.63 s, 6 H CH3 backbone

(TTP)TiCl3 7.23-.13 m, 8 H aromatic

(CDC13) 6.03 s, 1 H alkene
2.36 s, 6 H CH3 wry;
2.12 s, 6 H CH3 backbone

 

 

 

 

27

 

 

Figure 16 ORTEP Diagram of (TTP)2ZrCl2

28

 

 

 

 

 

 

(TI‘P)2ZrC12 was found to initiate the polymerization of 3,6—dimethyl—l,4-

dioxane-2,5—dione (dilactone) when combined with 4-tert-butylbenzyl alcohol at ~180
°C.47 Polymerization was identified by the appearance of a broad signals at ~5ppm and
1.53 ppm in ‘H NMR.

Initiation Step:

LnM\_OR
\ on

0 “Mt/0 Acyl o
Insertion \ cleavage LnM\O OH
H“ —’ 33° °
0

O O

 

. o
Propagation EH)"
0
0

Ya

n+1

Figure 17 Cationic Mechanism of Ring Opening Polymerization

Figure 17 shows the probable mechanism for the polymerization.“ Assuming this
mechanism, an alkoxide group would replace a chloride forming HCl. The generation of
HCl could destroy catalyst and is therefore undesirable. It also seems possible the alcohol
may displace the ligand instead of the chloride. Loss of ligand results in loss of any
possible reaction control. Complexes with alkoxides as initiating ligands are therefore
better candidates. Efforts to prepare L..M(OR)x type compounds have met with success

(vide infra).

29

 

 

 

 

 

 

Reaction of one equivalent of Li(TTP) with ZrCl4(THF)2 gives only ('ITP)2ZrClz.

However, Collins was able to make (PPP)ZrCl3 by reaction of (PPP)Zr(NMe2)3 with three

1.28 (TTP)ZrC13 was synthesized analogously.48

equivalents of Me3SiC

Reaction of one equivalent of Li(TTP) with TiCl4 gives (TTP)TiCl3 (4) as dark
purple crystals in 84% yield. The 1H NMR spectrum shows a larger downfield shift of the
backbone alkene proton (6.03 ppm) than in 3 (Table 1) An X-ray structure was obtained
(Figure 18 and Appendices). The titanium appears to be five coordinate square pyramidal
with chloride occupying the apical position and the other two chlorides and two nitrogens
at the basal positions. The metal is out the plane of the ligand and seems to interact with
the “It-system of the diketimine in an “115” fashion evidenced by the puckering of the
backbone. Lappert’s compound 1 is similar to 4. It also contains an out of plane metal,
which may indicate 115 character for the diketimine. The metal environment, in contrast to
4, is described as distorted trigonal bipyramidal.27

Reaction of one equivalent of Li(DDP) with freshly sublimed ZrCl4 gives
(DDP)ZrCl3 (5) as yellow crystals in 51 % yield. The isopropyl methyls appear as a pair
of diastereotopic doublets in the 1H NMR spectrum (Table 2). An X-ray crystal structure
(Figure 19 and Appendices) was determined. It showed the arrangement around the
zirconium to be square pyramidal. One of the chlorides resides at the apical position with
the other chlorides and the nitrogens basal. Others in our group have found that reaction
of (DDP)ZrCl3 with three equivalents of MeLi gives (DDP)ZrMe3 in moderate yield.“‘50

The X-ray structure of this compound shows the atoms around the metal to be arranged in

a square pyramid with a methyl group at the apical position.

30

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 2 1H NlVIR Data for (DDP)ZrCl3, (DDP)ZrCl3(T HF), (DDP)TiCl3, and

 

 

 

 

 

Li(DDP)

Compound 5 ppm Appearance Assignment l
Li(DDP) 7.16 m, 6 H aromatic
(C6D5) 4.86 s, l H alkene

3.10 sept, 4 H, J = 6.9 Hz CH(CH3)2
1.79 s, 6 H CH3 backbone
1.17 d, 12 H, J = 6.9 Hz CH3 isopropyl
1.14 d, 12 H, J = 6.9 Hz CH3 isopropyl
(DDP)ZrCl3 7.43-.20 m, 6 H aromatic
(CDCl3) 5.90 s, 1 H alkene
3.05 sept, 4 H, J = 6.9 Hz CH(CH3)2
1.94 s, 6 H CH3 backbone
1.37 d, 12 H J = 6.9 Hz CH3 isopropyl
1.18 d, 12 H, J = 6.9 Hz CH3 isopropyl
(DDP)ZrCI3(thf) 7.15 s, 6 H aromatic
(C5D6) 5.43 s, 1 H alkene
3.90 m, 4 H THF
3.58 sept, 4 H, J = 6.8 Hz CH(CH3)2
1.65 s, 6 H CH3 backbone
1.54 d, 12 H, J = 6.8 Hz CH3 isopmpyi
1.10 d, 12 H, J = 6.8 Hz CH3 isopropyl
1.05 m, 4 H THF
(DDP)TiCl3 7.20 m, 6 H aromatic
(CDCl3) 6.26 s, 1 H alkene
2.97 sept, 4 H, J = 6.6 Hz CH(CH3)2
2.00 s, 6 H CH3 backbone
1.33 d, 12 H J: 6.6 Hz CH3 isopropyl
1.11 d, 12 H, J = 6.6 Hz CH3 isopropyl

 

 

 

 

 

31

 

 

 

 

Reaction of one equivalent of Li(DDP) With ZrCl4(THF)2 gives (DDP)ZrCl3(THF)

(6) as small yellow crystals in 49% yield. The 1H NMR spectrum is very similar to
(DDP)ZrCl3 (Table 2). (DDP)ZrCl3(THF) was also formed by adding excess THF to
(DDP)ZrCl3.

Reaction of one equivalent of Li(DDP) with TiCl4(THF)2 was also attempted. The
crude 1H NMR spectrum exhibits a number of new resonances (Table 2). Especially
promising is the signal at 6.62 ppm assigned to the alkene backbone proton. This large
downfield shift from 4.87ppm (for Li(DDP), Table 2) suggests formation of a titanium
chelated compound ((TT P)TiC13 alkene proton resonance is 6.03 ppm). A new septet is
also apparent at 2.97 ppm as well as new isopropyl resonances (doublets at 1.33 ppm and
1.11 ppm). The initial 1H NMR spectrum strongly suggests the formation of a new
compound. Since (DDP)2ZrC12 is not known to form (presumably due to steric
restrictions imposed by the diisopropyl groups), it is assumed the smaller titanium
derivative ((DDP)ZTiClz) would be even less likely to form. Therefore, the new product is
proposed to be (DDP)TiCl3 (7) Unfortunately, attempts to further purify this compound

for l3C-NMR, X-ray, and other analyses were unsuccessful.

32

 

Figure 18 ORTEP Diagram of (TTP)TiCl3

33

 

 

 

 

     

Cllll

    

Zr(‘|)
1%

Figure 19 ORTEP Diagram of (DDP)ZrCl3

34

 

 

 

 

Synthesis of LMX3 and L2MX2 Type Compounds via Acid/Base Routes

Acid/base synthetic routes (Figure 20) were used to prepare LMX3 (X = We; for
M = Zr and Ti, X = CHzPh for M = Zr) and 14sz (X = NMez, M = Zr). The volatility of
the reaction byproducts, the lack of Li salt residues, and the further acid/base reactivity of
the remaining ancillary ligands make acid/base reactions attractive synthetic methods.

NM92
MezN NMe

Ph (Ph Ph I 2
@22an 0.133?

M Zr(CH2Ph)4 WNW?“ M = 2" Ti M

\/

(a) / (10) M = Zr
\©\ ©/ ( 1) M = Tl
- 07H8 45 C IN ”N
M TTPH Reflux

 

 

M (2r;
MezN l NM92

(9) N

(12)

Ph (235
<11) C T

 

Figure 20 Acid / Base Routes

Reaction of one equivalent of TTPH with Zr(CH2Ph)4 at room temperature for 8
hours yielded yellow crystals of (TTP)Zr(CH2Ph)3 (8) from toluene in 78% yield. An X-
ray structure of this compound was determined (Figure 22 and Appendices) which shows
a five coordinate zirconium in a square pyramidal environment. One of the benzyl
methylenes is at the apical position with the other two methylenes and two nitrogens

(from the nZ-coordinated TTP) at the basal positions. The room temperature 1H NMR

35

 

 

 

 

spectrum (Table 3) shows only one benzyl {CSOnance at 2.61 ppm, rather than the two

expected. This single resonance is maintained even at low temperatures. In contrast to the
NMR data, the X-ray structure shows one benzyl should not be equivalent to the other
two. The exchange of these benzyl groups must, therefore, be fast on the NMR time scale.

A second equivalent of 'ITPH was added to (TTP)Zr(CH2Ph)3 in an attempt to
prepare ('ITP)ZZr(CH2Ph)2. After heating at 45 °C for several hours, the 1H NMR
spectrum showed many new peaks, but no change in the TTPH signals. A NTVIR tube
sample of ('1'I'P)Zr(CH2Ph)3 alone was then heated for 48 hours at 45 °C in C6D6. The
resulting 1H NMR spectrum was clean and contained many new resonances with
complete loss of signals from starting material ((TTP)Zr(CH2Ph)3). From the NMR data,
it was apparent that toluene was formed. Also, two separate backbone methyl resonances
and two separate tolyl methyl resonances were observed suggesting a lower symmetry
structure. After integrating the 1H NMR spectrum, it was determined that only one
equivalent of toluene was lost. Based on the low symmetry and a downfield resonance at
7.80 ppm (1 H, assumed to be due to a lone carbene proton), the first structural proposal
was that a carbene had been formed through (it-hydrogen abstraction (Figure 21). If this
were the case, a pair of diastereotopic hydrogens would be expected for the remaining
benzyl methylene. Doublets at 2.13 and 1.66 ppm (J = 9.6 Hz) were assigned to be due to
such protons. Unfortunately, these signals corresponded to four hydrogens instead of two
expected for a carbene structure, so the proposed structure was incorrect.

A second formulation, (n3—MeC(NC7Hé)CHC(N—p—Tol)Me)Zr(T|2—CH2Ph)( n1—
CHzPh) ((TTP*)Zr(CH2Ph)2 (9)), resulting from an ortho-metallation of one of the tolyl

groups was proposed (Figure 21). This structure accounts perfectly for the NMR data

36

 

 

 

(Table 3). An X-ray structure was determiflCd for this compound, which supports the

proposed ortho-metallated structure (Figure 23 and Appendices). The tolyl group
coordinates to the zirconium at the carbon ortho to the nitrogen. The X-ray structure also
shows one benzyl group is 112, exhibiting a Zr-C,Pso interaction (Zr(1)-C(28) = 2.58 A) and
an acute C(21)-C(20)-Zr(1) angle of 83.58°. The structure of Zr(CH2Ph)4 has 85° as its
most acute C-C-Zr angle.49 The other benzyl group in 9 appears to be 111, which leads to
different environments for the two sets of methylene protons. This difference is not
apparent in the room temperature or low temperature 1H NMR spectra suggesting that the

exchange of the benzyl groups is rapid on the NMR time scale.

H"
(a) Eliminationof 0H7“, I /O
h (b) 1. Elimination of CM,
07H '3?" H. \ through Abstractionotl-P

a "1
Abstra

anew/fl § N/zr\N ( If \
M “

p cram/LG

11.. ”b \

Git-"CK /‘© @3125“?
M Qj “H imgammigdniiite

Four center transition state \ ‘ /

(b) 2. C-H' addition

2' across C=Zr
\
U C

Figure 21 Possible Thermolysis Mechanisms of (TTP*)Zr(CH3Ph)2

37

 

 

 

 

 

Table 3 1H NMR Data for (TTP)Zr(CH2Ph)3, ('I‘TP*)Zr(CH2Ph)2, and TTPH

 

 

 

 

 

Compound Sppm Appearance Assignment
TTPH 6.91 d, 4 H, J = 8.6 Hz aromatic
(C6D6) 6.84 d, 4 H, J = 8.6 Hz aromatic

4.81 s, 1 H alkene
2.10 s, 3 H CH3 tolyl
1.84 s, 3 H CH3 backbone
('I'I'P)Zr(CH2Ph)3 7.10 m, 6 H aromatic
(C6D6) 6.90 m, 7 H aromatic
6.73 m, 10 H aromatic
5.06 s, 1 H alkene
2.61 s, 6 H CH2 benzyl
2.09 s, 6 H CH3 tolyl
1.62 CH3 backbone
(TTP*)Zr(CH2Ph)2 7.80 m, 1 H aromatic
(C5D6) 7.18-6.75 m, 13 H aromatic
6.48 d, 4 H aromatic
5.31 s, 1 H alkene
2.33 s, 3 H CH3 tolyl
2.13 d, 2 H, J = 9.6 Hz CH2 benzyl
2.13 s, 3 H CH3 tolyl
2.07 s, 3 H CH3 backbone
1.66 d, 2 H, J = 9.6 Hz CH2 benzyl
1.58 s, 3 H CH3 backbonc

 

 

 

 

38

 

 

 

 

 

 

  
 
 
 
  
   

“C(25)

9 ‘=
(me) "”’ C(26)
A, "a
\? . A...
C(23) Rs 1% C(20)

C121) 4

5
C(22) (g

     
     

!\ C(12)
2.! 019)

Figure 22 ORTEP Diagram of (TTP)Zr(CH2Ph)3

39

 

 

 

 

 

Figure 23 ORTEP Diagram of the Thermolysis Product

40

 

There are two possible mechanisms by which this thermolysis could occur. The

toluene could be formed from a direct o-bond metathesis of a tolyl proton (H1) via a four
center transition state. This mechanism is illustrated in Figure 21(a). The abstracted
proton may also come from an adjacent benzyl ligand (H2) resulting in the evanescent
formation of a carbene. This formation would be followed by 1,2-addition of tolyl C—H
across a Zr=C bond (Figure 21(b)).

stay“ ail?

H2

da”!
”0

[:x’ Ti i\\\Me Toluene
’M\ Me 70- 100C

fifit flfi

Figure 24 Thermolysis of BenTiMe2 to (TwistBen)Ti

+2CH4

Similar alkyl elimination has been observed and studied in Schrock’s Ben ligand
system (Figure 6(0).43 BenTiMe2 eliminates two equivalents of methane to yield an
orthometallated product which Schrock refers to as TwistBen (Figure 24). Direct o-bond
metathesis and (it-abstraction followed by 1,2-addition of an ortho methyl across the
Ti=CH2 bond were proposed as possible mechanisms. Schrock prepared the deuterated
BenTi(CD3)2 and characterized the organic products of its thermolysis as only CD3H. It
was then concluded that the thermolysis of (Ben)TiMe2 proceeds via a direct o-bond
metathesis. Products expected for OL-abstraction-l,2-addition mechanism would be CD4

and CDsz.

41

 

 

 

 

 

 

To distinguish which mechanism might be at work in the case of

('ITP)Zr(CHzPh)3, deuterium-labeling studies were carried out in our groupsO

 

(PPP)Zr(CH2Ph)3 (PPP = 2-phenylarnin- 4 pi.-..,li...i..v 2 r ‘ ) and the perdeutero
(PPP-d‘°)Zr(CH2Ph)3 were prepared analogously to (PPP)Zr(CH2Ph)3. Thermolysis of
(PPP)Zr(CH2Ph)3 afforded (PPP-)Zr(CH2Ph)2 and toluene by NMR at 65 °C. Likewise,
(PPP-dl°)Zr(CH2Ph)3 undergoes thermolysis at 65 °C to form (PPP-d‘°-)Zr(CH2Ph)2 and
C5H5CH2D by NMR. A characteristic triplet for C6H5CH2D was observed at 2.08 ppm
(with J = 2 Hz). Formation of C6H5CH2D was also verified by GC-MS and independent
synthesis. This experiment provides strong evidence for direct o—bond metathesis (Figure
21(a)) as the mechanism for thermolysis of ('ITP)Zr(CH2Ph)3.

No reaction of Zr(CH2Ph)4 with DDPH was observed, even after heating at 100
°C for ten hours. Presumably, the isopropyl groups impose a kinetic barrier against alkyl
elimination.

Reacting Zr(NMe2)4 with TTPH at room temperature gave ('ITP)Zr(NMe2)3 (10)
as an orange-yellow solid in excellent yield (98%). The 1H NlVIR spectrum (Table 4)
suggests that the exchange of the NMe2 is rapid on the NMR time scale as only one signal
is observed instead of two. Collins has synthesized the phenyl substituted analog of this
compound (PPP)Zr(NMe2)3.28 The 1H NMR data for these two compounds are very
similar (chemical shift of (PPP)Zr(NMe2)3/(TTP)Zr(NMe2)3): backbone alkene proton
(5.01/5.10 ppm), dimethylamine protons (2.73/2.80 ppm), backbone methyls (1.75/1.75
ppm). Suitable crystals for single crystal X-ray diffraction were grown from pentane and
since no structure had been previously reported, a data set was collected and solved

(Appendices). The ORTEP diagram in Figure 25 shows the nitrogens arranged around the

42

 

 

 

 

 

 

 

 

 

zirconium in a trigonal bipyramid orientation. Zr, N(2), N(3), and N(4) can be considered

coplanar with the summation of the angles between them being 358.7°. Planarity
observed in NMe2 groups (average of Eng,“ 359.7°) is consistent with n—donation to the
metal.

The titanium analogue of this compound was synthesized in the same manner
from Ti(NMe2)4 and 'I'I‘PH. Heating overnight at 35 °C was required to complete the
reaction. Large orange crystals of (TTP)Ti(NMe2)3 (11) were obtained from pentane in
87% yield. The 1H NMR data is comparable to ('ITP)Zr(NMe2)3 (Table 4). An X-ray data
set was solved for this compound in order to compare it to ('ITP)Zr(NMe2)3 (Figure 26
and Appendices). The nitrogens of this compound also adopt a distorted trigonal
bipyramidal arrangement around the titanium, and the NMe2 groups are planar (21,331cs

359.6°) as in compound 10.

43

 

 

 

 

il|.-.- l

 

 

Table 4 1H NMR Data for (TTP)Zr(NMez)3, (TTP)Ti(NMe2)3 and (TTP)2Zr(NMe2)2

 

 

 

 

 

Compound 8 ppm Appearance Assignment
('ITP)Zr(NMe2)3 6.98 d, 4 H, J = 8 Hz aromatic
(C6D6) 6.76 d, 4 H, J = 8 Hz aromatic
5.10 s, 1 H alkene
2.80 s, 18 H N(CH3)2
2.12 s, 6 H CH3 tolyl
1.75 s, 6 H CH3 backbone
(”I'I‘P)Ti(NMe2)3 6.95 d, 4 H, J = 8 Hz aromatic
(C6D6) 6.65 d, 4 H, J = 8 Hz aromatic
5.21 s, 1 H alkene
2.95 s, 18 H N(CH3)2
2.13 s, 6 H CH3 tolyl
1.78 s, 6 H CH3 backbone
(TTP)2Zr(NM62)2 7.25 br s, 2 H aromatic
(C6D6) 7.07 m, 2 H aromatic
6.87 m, 3 H aromatic
5.67 d, 1 H, J = 3 Hz aromatic
5.13 s, 1 H alkene
2.64 br s, 6 H N(CH3)2
2.22 s, 3 H CH3 tolyl
2.06 s, 3 H CH3 tolyl
1.77 s, 3 H CH3 backbone
1.43 s, 3 H CH3 backbone

 

 

 

 

 

 

 

 

 

 

Figure 25 ORTEP Diagram of (T TP)Zr(NMe2)3

45

 

 

 

Figure 26 ORTEP Diagram of (TTP)Ti(NMe2)3

46

’D
A,

 

Adding a second equivalent of TTPH to ('ITP)Zr(NMe2)3 (or reacting 2 : 1, TTPH
: Zr(NMe2)4) results in the formation of ('I'I‘P)2Zr(NMe2)2 (12) after heating at 90 °C for
five hours. Recrystallization from pentane gave a 58% yield as orange-yellow crystals.
Collins has also synthesized the phenyl analog ((PPP)2Zr(NMe2)2) of this compound.”
The 1H NMR spectrum for ('ITP)2Zr(NMe2)2 (Table 4) is analogous to (PPP)2Zr(NMe2)2.
In both compounds two backbone methyl resonances are observed (and two tolyl methyl
signals in 12) indicating a cis arrangement of the dimethylamines in an octahedral
geometry. Both compounds also display an unusually high field doublet (5.67 ppm for 12
and 5.8 ppm for (PPP)2Zr(NMe2)2). This signal is due to an ortho hydrogen on an
aromatic ring that is located directly over the shielding cone of an opposite aromatic ring.
The proton experiences strong shielding causing it to resonate at higher field. No X—ray
data were collected on 12, as the structure of (PPP)2Zr(NMe2)2 had already been reported.
It adopts the anticipated distorted cis octahedral geometry and shows the ‘upfield’ ortho
aromatic hydrogens pointing into the opposite rings. Due to the strong spectroscopic
similarities, it is assumed that 12 exhibits the same structure as (PPP)2Zr(NMe2)2.
Attempts to prepare the titanium analog, (TTP)2Ti(NMe2)2, from one equivalent of TTPH
and (TTP)Ti(NMe2)3 or two equivalents of 'I'I‘PH to one equivalent of Ti(NMe2)4 were

unsuccessful even after refluxing overnight in toluene.

M Me
a Ti(NMo,)4 m exN/

\
DTPH

Figure 27 Transamination to form DTPH

47

 

 

 

 

 

 

Previous work in our group has shown that reaction of TPH (TPH = 4-p-

tolylimino-pent—4-en-2-one) with Ti(NMe2)4 results in a transamination to form 2-
(dimethylamino)-4-(4—tolylimino)pent-2-ene (DTPH) (Figure 27).45 Such transaminations
have precedent.51 After comparing 1H and 13C-NMR data, it was apparent that reaction of
TPH with Zr(NMe2)4 does not result in transamination to form DTPH. Rather,
(TP)2Zr(NMe2)2 (13) is formed as yellow crystals in 66% yield. This difference was
immediately evidenced by the difference in the shift of the diagnostic alkene hydrogen on
the ligand backbone. The value is 5 4.76 ppm for DTPH compared to 8 6.66 ppm for
(TP)2Zr(NMe2)2 (Table 5). The melting point of (TP)2Zr(NMe2)2 is also much higher at
164—6 °C than that of DTPH at 35-6 °C. Reaction of (TP)2Zr(NMe2)2 with two
equivalents of Me3SiC1 gave the previously characterized (TP)2ZrCl245 (by ‘H NMR (all
signals match)).

Recalling that ('ITP)Zr(NMe2)3 forms readily at room temperature and
('ITP)2Zr(NMe2)2 requires reflux in toluene, reaction of one equivalent of Zr(NMe2)4 and
one equivalent of TPH gives (TP)2Zr(NMe2)2 as the only product at room temperature.
The difference in reactivity may be due to a more acidic proton in the monoketimine. The
decrease in steric properties from the diketimine to the monoketimine ligand may also
encourage the amine elimination.

The X-ray structure was solved for this compound (Figure 28 and Appendices)
which confirmed the coordination of two equivalents of TP resulting in an octahedral
arrangement around the metal. The oxygen atoms are arranged trans to each other. This

trans arrangement is also observed in the X-ray structures of (TP)2ZrCl2 and (TP)2TiCl2.45

48

 

 

 

 

The dimethyl amido ligands are again more or less planar indicating considerable 1r

donation.

Attempts to prepare (DDP)Zr(NMe2)3 from DDPH and Zr(NMe2)4 resulted in no
reaction even after refuxing in toluene for ten hours. The ligand salt (DDP)H (HCl) was
then added to a toluene solution of Zr(NMe2)4 at —77 °C. The reaction mixture was
allowed to warm to room temperature over one hour. The toluene was removed and the
solid was recrystallized from pentane to give small white crystals of (DDP)ZrC1(NMe2)2
(14) in 51% yield. The 1H NMR resonances of this compound are very broad at room
temperature, but sharpen at 50 °C (Table 5). An X-ray structure was obtained from one of
the white crystals (Figure 29 and Appendices). There are two crystallographically unique
molecules in the unit cell. The coordination around the Zr is distorted square pyramidal
with one of the amine nitrogens in the apical position and the other three nitrogens and
the chloride situated at the basal positions. The amino groups again indicate 1: donation
with Eagles = 359.8°.

The reaction is probably facilitated by the protonolysis of one of the amido groups
to give ZrCNMe2)3Cl. With the reduced sterics, a second aminolysis can proceed with loss
of another equivalent of HNMe2 to give (DDP)ZrC1(NMe2).

This synthetic avenue may be useful if it proves to be general for various ligands
and salt anions (Figure 33). Addition of a second equivalent of ligand followed by
alcoholysis leads to single site species in which the X group can directly tune the metal
electronics. Also, alkylating the chloride site with LiR, followed by alkyl abstraction
could lead to single site cationic compounds. Coupling with other observed acid / base

chemistry (Vida infra) might lead to formation of a cationic imine compounds (Figure 33).

49

 

 

 

Table 5 1H NMR Data for (TP)2Zr(NMe2)2, (DDP)ZrCl(NMe2)2 and

 

 

 

 

 

(TTP)Zr(NMez)(NCeH¢CH3)
Compound 8 ppm Appearance Assignment
(TP)2Zr(NMe2)2 6.97 s, 2 H aromatic
(C6D6) 6.94 s, 1 H aromatic
6.66 s, 1 H aromatic
4.95 s, 1 H alkene
3.30 s, 6 H N(CH3)2
2.16 s, 3 H CH3 tolyl
1.56 s, 3 H CH3 backbone
1.42 s, 3 H CH3 backbone
(DDP)ZrCl(NMe2)2 7.12 s, 6 H aromatic
(C6D6) at 50 °C 5.20 s, 1 H aromatic
3.03 sept, 4 H, J = 6.9 Hz alkene
2.70 s, 12 H N(CH3)2
1.63 s, 6 H CH3 tolyl
1.37 d, 12 H, J = 6.8 Hz CH3 backbone
1.15 d,12H,J=6.8Hz
(TTP)2Zr(NMe2)(p-NC6H4Me) 6.91 d, 6 H, J = 7.8 Hz aromatic
(C6D6) 6.74 d, 4 H, J = 8.1 Hz aromatic
6.36 d, 2 H, J = 8.1 Hz aromatic
5.30 s, l H alkene
2.78 s, 6 H NC6H4CH3
2.26 s, 3 H N(CH3)2
2.11 s, 6 H CH3 [0in
1.82 s, 6 H CH3 backbone

 

 

 

 

50

 

 

 

 

     

If///‘. Ifi/A‘
C(27) $2)? ‘
z; ‘
‘\ , 1 I
_ s. C(25)

0(1) (7%.

Figure 28 ORTEP Diagram of (TP)2Zr(NMe2)2

51

 

 

 

Kn? )
"é‘! C(32

 

”// ,. * Q
' C13 3) .3
I iillglfiim 4) '\\\Q
\ V [33‘

Figure 29 ORTEP Diagram of (DDP)ZrCl(NMe2)2

52

 

Further Acid/Base Chemistry

An attractive feature of compounds 10-15 is the possibility of replacing the NMe2
groups through further acid/base chemistry. Initial exploration of this chemistry for
compounds 10 and 12 has been successful. Assuming that the NMe2 groups on
('ITP)Zr(NMe2)3 are more basic than TTP, ('ITP)Zr(NMe2)3 was reacted with one
equivalent of p-toluidine at room temperature (Figure 30). Comparing the resulting 1H
NMR data (Table 5) to that of starting materials suggests that the product of the reaction
is ('ITP)Zr(NMe2)(p-NC6H4Me) (15). The shift of the alkene proton from 8 5.10 to 5.30
ppm is the first indication of a reaction. Integrating the peaks in the methyl region reveals
a 6 H26 H6 H3 H ratio corresponding to two sets of 6 H from the ligand (backbone and
tolyl methyls), 6 H from the dimethyl amine and 3 H from the toluidine methyl. Attempts
to further purify the product through recrystallization were unsuccessful. Solubility
problems hampered efforts to collect l3C-NMR data. Reaction of ('ITP)Zr(NMe2)3 with
2,4,6-tlimethylaniline was also attempted. Some reaction occurred, but no tractable
product was obtained. Further investigation into these ‘imines’ is warranted. These four

coordinate zirconium compounds may exhibit interesting chemistry.

NM82 d

M92N\ I NMe2 M

N N
nN/ZKE/g/ aniline bf \Zr//

N/ \N

MMM

Figure 30 Aminolysis to Form an Imine

Other acid/base chemistry with the compounds of the type LM(NMe2)3 and

L2M(NMe2)2 has been observed in our group. Alcoholysis reactions (Figure 31) of these

53

 

 

 

 

 

 

 

 

 

 

52

compounds to yield the alkoxide derivatives have proven successful in some cases.
(TTP)2Zr(NMe2)2 was reacted with two equivalents of methanol, p-cresol (4-methy1
phenol) and 4-tert—butylbenzyl alcohol to give ('ITP)2Zr(OMe)2, ('ITP)2Zr(OC6H4Me)2
and (TTP)2Zr(OCH2C6H4-t-butyl)2 respectively in good yields. Reaction of
(’ITP)Zr(NMe2)3 with three equivalents of methanol gave a low yield (< 5%) of
(TTP)Zr(OMe)3. Reaction of ('ITP)Zr(NMe2)3 and (TTP)Ti(NMe2)3 with p-cresol and 4-

tert-butylbenzyl alcohol resulted in intractable products.

R Fl

’ /
R—m.~“NM62 2 ROH R—Q ,,\\0Fl
.. r.
Fl

_.-_

Zr 3
_ / I‘NMe2 R_ / l‘on
U\R U\

 

R
M92” M90
NMe
~ / \ : [Zr\
Ar N N-Ar Ar‘N N—Ar

Figure 31 Alcoholysis of LM(NMe2)3 and LzM(NMe2)2

Preliminary polymerization experiments with 3,6-dimethyl-l,4—dioxane-2,5-dione
(dilactone) have been performed to survey the potential of these compounds.52 All four
compounds catalyze polymerization of dilactone as determined by the appearance of two
broad signals in 1H NMR spectra (5.13 and 1.53 ppm). Integration of monomer signals to
polymer signals suggests that the order of activity is roughly (temperature of
polymerization) ('ITP)2Zr(OMe)2 (at 80-100 °C) < ('ITP)Zr(OMe)3 (at 80-100 °C) <
('ITP)2Zr(OC61-14Me)2 (at 50-60 °C) < ('ITP)2Zr(OCH2C6I{4-t-butyl)2 (at 40 °C). Though

these results are preliminary, it is obvious from the temperature ranges alone, that the

54

 

 

 

 

 

 

alkoxides (catalyzing polymerization at 40 °C) are indeed better polymerization catalysts
than the dichloride compound (('ITP)2ZrCl2, at ~180 °C). More detailed polymerization

experiments are in progress.

CONCLUSIONS

Initial investigation of group 4 B—diketimines has shown their synthesis to be
simple and versatile. The potential for preparing a much larger family of interesting
compounds via acid/base and salt metathesis routes is clear (Figure 33). With this large
library of derivatives available, the prospects for performing stereospecific
polymerization remain bright. For example, the reaction below (Figure 32) suggests how
a derivative of trans-1,2-diaminecyclohexane might react with ('ITP)Zr(NMe2)3. The
chirality of the trans-1,2-diaminecyclohexane derivative would be imposed on the
complex. Once formed, the remaining dimethylamine might be replaced with an alkoxide

through alcoholysis, leaving a single site chiral catalyst.

ZF(NM92)4 + l .__—p MGZN - Zf ‘

Figure 32 Proposed Aminolysis Reaction

55

 

 

 

 

Most Ziegler-Natta catalysts are presumed to initiate polymerization via a cationic

species formed in situ. Alkyl abstraction reagents such as [Ph3C][B(C6F3)4] and the strong
Lewis base B(C(,F5)3 have been used to form such cationic species in metal alkyl and
metal amine compounds. [B(C5Fs)4] is generally too large to coordinate the metal as a
ligand and instead results in generation of a cationic species. Our systems polymerize
dilactones without activation. Accessing cations may improve catalytic activity. Figure 33

suggests some possible routes to cationic species.

 

M(NM92)4
+
X=Cl, F, OTs, etc. [ ,r s z x X
— N—A
Ar N H r
M NH2Ar A ‘N + [B(C6Fs)41'
x 21x” 92 2. UR u

 

N 1. LH M
,h I ‘\\ g- 28“ Ar~NM N,Ar 3. Ph3C[B(CaF5)4] Ar\N Wm
in

0.2:... .'_ M M

1. LH
2. ROH
PhsC[B(Cst)4]

N + {B(Cst)41' Ag[B(CeF5)4] /m
I], .\\ <— ROv “‘1 vX
R0' | N
N

Figure 33 Other Possible Reactivity

56

 

 

 

 

CHAPTER 3

EXPERIMENTAL METHODS

Instrumental Procedures

1H NMR spectra were recorded on Varian Gemini—300, Varian VXR-300, and
INOVA—300 (299.949 MHz) spectrometers and referenced to residual proton solvent
signals. l3C spectra were recorded using Varian VXR-300 and INOVA-300 spectrometers
operating at 75.430 MHz. Carbon chemical shifts are referenced to solvent signals. Low
resolution mass spectra were obtained from powder samples on a portable Trio-l VG
Masslab Ltd. mass spectrometer. Analysis for carbon, hydrogen, and nitrogen were
performed on a Perkin Elmer CHN 2400 Series II CHNS/O Analyser at the chemistry
departement of Michigan State University or from Desert Analytics in Tucson, AZ.
Single Crystal X-Ray Structure Determination

Unless otherwise noted, all crystals were considered to be air sensitive and were
collected by filtration and coated with Paratone—N. A suitable single crystal was selected
and mounted onto a glass fiber (with Paratone-N). The crystal was then transferred to the
goniometer of a Siemens SMART CCD diffractometer using Mo K, radiation (A =
0.71073 A). Data were collected as 30 second per frame at 173 K. The initial cells were

calculated by the Smart from three sets of 15 frames. All data sets were collected over a

57

 

 

 

hemsPhere of reciprocal space. SAINT was used to integrate 1025 frames and to generate

the raw file. Final unit cell parameters were obtained by least—squares refinement of
strong reflections obtained. Absorption correction and time decay were applied to the data
by SADABS. The non-hydrogen atoms located by using SHELXS—86 and refined using.
(TTP)2ZrCl2 (3). Large yellow crystals were grown from pentane/toluene at —30 °C. A
data set was collected, solved, and refined in the space group P21/n by direct methods.
(TTP)TiCl3 (C7113) (4). Small dark purple crystals were grown from pentane/toluene at —
30 °C. A data set was collected, solved, and refined in the space group PT by direct
methods.
(DDP)ZrCl3 (5). Small almost colorless crystals were grown from pentane/toluene at —30
°C. A data set was collected, solved, and refined in the space group ana by direct
methods.
(TTP)Zr(CH2Ph)3 (8). X-ray quality crystals were grown from toluene/pentane at —30
°C. A data set was collected, solved and refined in the space group C2/c by direct
methods.
(TTP*)Zr(CH2Ph)2 (9). Large orange round X-ray quality crystals were grown from
pentane/toluene at —30 °C. A data set was collected, solved, and refined in the space
group PT by direct methods.
(TTP)Zr(NMe2)3 (10). Large, yellow, X-ray quality crystals were grown from
pentane/toluene at —30 °C. A data set was collected and partially solved in the space
group P1. All inversion center between the two ‘independent molecules’ was observed.
Its location was determined by calculating the difference of the absolute values of the x,

y, and z coordinates for symmetrically related nitrogens. One of the two molecules was

58

 

 

 

then discarded and the origin redetermined. The space group was changed to PT and

solved using direct methods.

(T TP)Ti(NMe2)3 (11). Large orange X-ray crystals were grown from pentane at —30 °C.
A data set was collected, solved, and refined in the space group PT by direct methods.
(TP)2Zr(NMe2)2 (13). Small yellow crystals were grown from pentane/toluene at —30 °C.
A data set of strong reflections was collected, solved and refined in the space group P21/c
by direct methods.

(DDP)ZrCl(NMe2)2 (14). Small colorless crystals were grown from pentane at —30 °C. A
data set was collected, solved, and refined in the space group PT by direct methods.
There are two molecules in the unit cell. .

Syntheses

Materials and General Considerations

For compounds 3-15, all manipulations were performed using glove box, Schlenk

or vacuum-line techniques. Argon and nitrogen were purified by passage through a
column of MnO supported on silica. All solvents (except NMR solvents) were freshly
distilled over sodium/benzophenone ketyl and were saturated with dinitrogen before use.
Chloroform—d] was dried over 4 A sieves. Benzene-d6 was dried over 4 A molecular
sieves, and vacuum transferred to a sodium-mirrored air-free flask. Uncorrected melting
points of crystalline samples in sealed capillaries (under argon) were reported. 2,4—
pentadione, 3,5-bis(tert—butyl) phenol, and p-tolysulfonic acid were purchased from
Aldrich and used as received. p-toluidine and 2,6-diisopropyl aniline were purchased
from Aldrich, then sublimed and distilled respectively prior to use. ZrCl4 and TiCl4 were

purchased from Aldrich. They were sublimed and distilled respectively prior to use. 3,5-

59

 

 

 

di~tert-butylphenyl bromide53, 3,5-di-rert—butylphenyl boronic acids4 and 3,5-bis(3,5-di-

tert-butylpheny1)-nitrobenzene55 were prepared using literature methods. 3,5-bis(3,5-di-
ten-butylphenyl)-aniline was prepared by reducing 3,5-bis(3,5-di-tert—butylphenyl)-
nih‘obenzene with two equivalents of Sn and an excess of concentrated HCl in refluxing
thf. KOH was added and the solution was filtered to obtain the free base in 85% yield.
ZrCl4(thf)2,56 TiCl4(thf)2,56 Zr(CH2Ph)4,57 Zr(NMe2)4,58 and Ti(NMe2)459 were prepared
literature methods.

4-(3,5-bis(3,5-di-tert-butylphenyl)-phenylimino)-pent-4-en-2-one (2a). 2,4-pentadione
(1.1 mL, 11 mmol), 3,5-bis(3,5-di-tert-butylphenyl)-aniline (4.61 g, 9.81 mmol), 60 mL
of toluene, and p-tolylsulfonic acid (10 mg, 0.053 mmol) were placed into a 250 L round
bottom flask fitted with a Dean-Stark apparatus. The reaction mixture was refluxed
overnight with vigorous stirring. The solvent was removed under vacuum leaving a
yellow solid (5.32 g, 98%). mp 220-223 °C. 1H NMR (CDCl3) 8 12.62 (s, 1 H, OH), 8
7.58 (s, 1 H, aromatic H), 8 7.46 (s, 2 H, aromatic H), 8 7.41 (s, 4 H, aromatic H), 8 7.27
(s, 1 H, aromatic H), 8 5.23 (s, 1 H, CH3C(NAr)CHC(OH)CH3), 8 2.12 (s, 3 H, CH3
backbone), 8 2.09 (s, 3 H, CH3 backbone), 8 1.36 (s, 36 H, CH3 ovum); 13C{1H} NMR(CDC13) 8

;EI/MS: M“r m/z 551.3.

 

2 p ‘ '3' ' 4 p ‘ '3" ' 2 r ‘ (TTPH) (general method). 2,4-pentanedione,
p—toluidine, and a very small amount of p-tolylsulfonic acid were heated at reflux
overnight in toluene. The solvent was removed giving TTPH-(HCl). The free base was

obtained by addition of KOH.

 

2-(2,6-diisopropyl)phenylamino-4-(2,6-diisupiowl; ' 12--.Z- - 2 ‘ (DDPH)

U 1‘

(general method). 2,4-pentanedione (1 equiv) and 2,6—diisopropyl aniline (1 equiv) was

60

 

 

heated in a Dean Stark apparatus overnight in refluxing toluene. The solvent was
removed giving the monodiketime DPH. DPH (1 equiv), 2,6-diisopropyl aniline (1 equiv)
and p—tolylsulfonic acid (1 equiv) were heated in a Dean Stark apparatus overnight in
refluxing toluene. The solvent was removed and KOH was added to give the free base
DDPH. Very pure DDPH was obtained as long rods when recrystallized from pentane and
a small amont of ethanol.
(TTP)2ZrCl2 (3). 5—mL of a toluene solution of Li(TTP) (1.55g, 5.45 mmol) was cooled
to ——78 °C, and added dropwise to a stirred suspension of ZrC14(thf)2 (1.1 1 g, 2.72 mmol)
in 5 mL of toluene which was also at —78 °C. A yellow solid precipitated when the
reaction mixture was allowed to warm to room temperature. The solution was filtered via
cannula and the solid was extracted several times with hot toluene. The filtrates were
combined, and the volume was reduced under vacuum and a yellow-green solid was
recrystallized from toluene/pentane (0.98g, 50%). mp >250 °C. 1H NMR (CDCl3) 8 7.01
(d, J = 8.1Hz, 4 H, C6H4CH3), 8 6.71 (br s, 4 H, C6H4CH3), 5.34 (s, 1 H,
CH3C(NAr)CHC(NAr)CH3), 2.28 (s, 6 H, C6114CH3), 1.63 (s, 6 H,
CH3C(NAr)CHC(NAr)CH3); l3C{'H} NMR(CDC13)8 166.29, 146.03, 135.11, 128.61,
127.73, 105.32, 25.12, 20.96. Anal.so Calcd for C33H42N4Cl2Zr: C, 63.66; H, 5.90; N,
7.81. Found: C, 63.70; H, 6.67; N, 7.78.
(T TP)TiCl3 (4). Li(TTP) (1.43g, 5.03 mmol) dissolved in 10 mL of toluene was added to
a stirred solution of TiC14(toluene) (2.6 mL of 1.82 mol/L, 0.47 mol) at room
temperature. The solution turned dark immediately upon addition and was slightly
exothermic. The reaction mixture was allowed to stir for 2 h. The dark solution was

removed via cannula and the remaining dark solid was extracted with hot toluene. The

61

 

 

 

 

 

filtrates were combined and their volume was reduced under vacuum. Dark purples were
grown at —80 °C. (1.6 g, 84%). mp 125 °C. 1H NMR (CDCl3) 8 7.23-7.13 (mult, 8 H,
C6H4CH3); 6.03 (s, 1 H, CH3C(NAr)CHC0~IAr)CH3); 2.36 (s, 6 H, C6H4CH3); 2.12 (s, 6
H, CH3C(NAr)CHC(NAr)CH3); 13C{'H} NMR (CDCl3) 5 159.82, 146.62, 129.73,
123.82, 104.86, 22.72, 21.12. Anal. Calcd for C26H29N2C13Ti: C, 59.62. H, 5.58; N, 5.35.
Found: C, 59.29; H, 5.33, N, 5.22.
(DDP)ZrCl3 (5). Li(DDP) (830 mg, 2.2 mmol) dissolved in 2 mL of toluene was added
dropwise to a stirred suspension of mu (freshly sublimed) (500 mg, 2.1 mmol) in 2 mL
of toluene. Several toluene washings (3 x 1 mL) were used to ensure complete Li(DDP)
transfer. Once the addition was complete, the solution was allowed to stir overnight at 60
°C. The solution was removed via cannula while warm. The solvent was removed from
the filtrate under vacuum. The remaining orange solid was recrystallized from CH2C12 at
—80 °C yielding small slightly yellow crystals (670 mg, 50.7%). mp >220 °C. 1H NMR
(CDCl3) 8 7.34—7.20 (m, 6 H, C6H3(CH(CH3)2)), 5.90 (s, 1 H,
CH3C(NAr)CHC(NAr)CH3), 3.05 (septet, JHH = 6.9, 4 H, C6H3(CH(CH3)2)), 1.94 (s, 6
H, CH3C(NAr)CHC(NAr)CH3), 1.37 (d, JHH = 6.9, 12 H, C6H3(CH(CH3)2)2), 1.18 (d,
.111]; = 6.9, 12 H, C6H3(CH(CH3)2); l3C{‘H} NMR (CDCl3) 5171.3, 146.6, 141.7,
127.8, 124.6, 104.9, 29.1, 26.2, 24.7, 24.6; Anal.so Calcd for czgmlNzcbzh c, 56.53; H,
6.71; N, 4.54. Found: C, 56.54; H, 6.59; N, 4.42.
(DDP)ZrCl3(thf) (6). Li(DDP) (450 mg, 1.15 mmol) dissolved in 2 mL of toluene was
added dropwise to a stirred suspension of ZrCl4(tht)2 (430 mg, 1.14 mmol) in 2 mL of

toluene at room temperature. Several toluene washings (3 x 1 mL) were used to ensure

62

 

 

 

 

800d Li(DDP) transfer. After the addition was complete, the solution was allowed to stir
overnight. The clear orange solution was filtered off via cannula. The volume of solution
was reduced under vacuum and then cooled to —80 °C yielding small yellow crystals (390
mg, 49%). mp >225 °C. 1H NMR (C6D6) 8 7.15 (s, 6 H, C6H3(CH(CH3)2)2), 5.43 (s, 1
H, CH3C(NAr)CHC(NAr)CH3), 3.90 (mult, 4 H, thf), 3.58 (septet, JHH = 6.8, 4 H,
C6H3((CH(CH3)2)2), 1.65 (s, 6 H, CH 3C(NAr)CHC(NAr)CH 3) )), 1.54 (d, JHH = 6.8, 12
H, C6H3(CH(CH3)2)2), 1.10 (d, JHH = 6.8, 12 H, C6H3(CH(CH3)2)2), 1.05 (mult, 4 H,

thf); 13C{‘H} NMR (Cam) 5 169.33, 145.86, 144.08, 124.76, 105.64, 77.00, 28.93,
26.45, 25.66, 24.82, 24.74;

(DDP)TiCl3 (7). Li(DDP) (300g, 0.9 mmol) dissolved in 2 mL of toluene was added
dropwise to TiCl4(thf)2 (380mg, 0.9 mmol) in 2 mL of toluene at —78 °C. Upon addition,
the solution turned dark. The reaction mixture was allowed to warm to RT and stir
overnight. The solution was removed via filter stick. The remaining dark sticky substance
was pumped on yielding a flaky dark solid. Purifying the product further proved difficult;
lH NMR (CDCl3) 8 7 (m, 6 H, C6H3(CH(CH3)2)2), 6.26 (s, 1 H,
CH3C(NAr)CHC(NAr)CH3), 2.97 (septet, JHH = 6.6, 4 H, C6H3(CH(CH3)2)2), 2.00 (s, 6
H, CH 3C(NAr)CHC(NAr)CH3), 1.33 (d, JHH = 6.6, 12 H, C6H3(CH(CH3)2)2) )), 1.11 (d,
JHH = 6.6, 12 H, C6H3(CH(CH3)2)2),

(TTP)Zr(CH2Ph)3 (8). TTPH (1.97g, 7.08 mmol) dissolved in 20 mL of toluene was
added dropwise to a stirred solution of Zr(CH2Ph)4 (3.21g, 7.05 mmol) dissolved in 5 mL
of toluene. The reaction mixture was allowed to stir for 8 hours. The volume was reduced

under vacuum and the solution was placed in the -80 °C freezer. A yellow solid

63

 

 

 

ill| .IF

 

precipitated. (3.55g, 78%). mp” 98-100 °C. ‘H NMR (c619,) 5 7.10 (mult, 6 H,
aromatic), 6.90 (mult, 7 H, aromatic), 6.73 (mult, 10 H, aromatic), 5.06 (s, 1 H,
CH3C(NAr)CHC(NAr)CH3), 2.61 (s, 6H, CH2C6H5), 2.09 (s, 6 H, C6114CH3), 1.62 (s, 6
H, CH3C(NAr)CHC(NAr)CH3); 13C{1H} NMR (C6D6) 5 160.58, 146.68, 143.52, 135.63,
130.02, 128.77, 127.65, 126.03, 121.84, 102.14, 75.62, 22.76, 20.84. Anal.so Calcd for
CaoHa2NzZr: C, 74.83; H, 6.59; N, 4.36. Found: C, 74.44; H, 6.56; N, 4.60.
(TTP*)Zr(CH2Ph)2 (9). ('ITP)Zr(CH2Ph)3 (1.1 g, 1.7 mmol) was dissolved in 5 mL of
toluene and heated at 45 °C for 48 hours. The solvent was removed under vacuum.
Orange-yellow crystals were obtained from toluene/pentane (1:1) at —-30 °C (0.64 g,
68%). mp 140-142 °C. 1H NMR (C6D6) 8 7.80 (mult, 1 H, aromatic), 7.18-6.75 (mult, 13
H, aromatic), 6.48 (d, J = 9.0 Hz, 4 H, aromatic), 5.31 (s, 1 H,
CH3C(NAr)CHC(NAr)CH3), 2.33 (s, 3 H, C6HaCH3), 2.13 (d, J = 9.6 Hz, 2 H,
CH2C6I-15), 2.13 (s, 3 H, C6114CH3), 2.07 (s, 3H, CH3 backbone), 1.66 (d, J = 9.6 Hz, 2 H,
CH2C6I-15), 1.58 (s, 3 H, CH3 backbone); l3C{'H} NMR (c611,) 5 186.86, 159.11, 158.52,
141.80, 138.85, 137.45, 132.63, 130.44, 129.96, 129.84, 129.26, 128.17, 122.90, 118.71,
106.46, 66.62, 24.62, 24.23, 21.60, 20.90; Anal.so Calcd for C33H34NzZr: c, 72.08; H,
6.23; N, 5.09. Found: C, 71.90; H, 6.46; N, 4.70.

(T TP)Zr(NMe2)3 (10). 'ITPH (1.30g, 0.467 mmol) dissolved in 2 mL of toluene was
added dropwise to a stirred solution of Zr(NMe2)4 (1.25g, 0.467 mmol) dissolved in 2 mL
of toluene at room temperature. After stirring for 1 hour, the toluene was removed under
vacuum leaving an orange-yellow solid (2.26g, 98%). mp 117-119 °C. 1H NMR (C6D6) 8

6.98 (d, J = 8 Hz, 4 H, C6H4CH3), 6.76 (d, J = 8 Hz, 4 H, C6H4CH3), 5.10 (s, 1 H,

 

 

 

 

 

 

CH3C(NAr)CHC(NAr)CH3), 2.80 (s, 18 H, N(CH3)2), 2.12 (s, 6 H, canary, 1.75(s, 6

H, CH3C(NAr)CHC(NAr)CH3); 13C{lH} NMR (C6116) 8 164.54, 148.26, 133.04, 129.15,
125.08, 100.23, 42.41, 24.21, 20.84. Anal.50 Calcd for C25H39N52r: C, 59.95; H, 7.85; N,
13.98. Found: C, 59.59; H, 7.48; N, 13.89.

(T TP)Ti(NMe2)3 (11). TTPH (3.8g, 13.8 mmol) in 5mL of toluene was added dropwise
to a stirred solution of Ti(NMe2)4 (3.36g, 13.8 mmol ) at room temperature. The reaction
mixture was heated at 35 °C overnight. The toluene was removed under vacuum. Orange
crystals formed from pentane at -80 °C. (5.5g, 87%). mp 140-143 °C. 1H NMR (C6D6) 8
6.95 (d, J = 9 Hz, 4 H, C6H4CH3) 6.65 (d, J = 9.0 Hz, 4 H, C6H4CH3), 5.21 (s, 1 H,
CH3C(NAr)CHC(NAr)CH3), 2.95 (s, 18 H, N(CH3)2), 2.13 (s, 6 H, C6114CH3), 1.78 (s, 6
H, CH3C(NAr)CHC(NAr)CH3); '3C{IH} NMR (C6D6) 8 162.81, 150.16, 132.28, 128.57,
124.70, 100.24, 46.23, 24.43, 20.84; Anal. Calcd for C23H39N5Ti: C, 65.63; H, 8.59; N,
15.31. Found: C, 65.70; H, 8.75, N, 15.01.

(T TP)2Zr(NMe2)2 (12). TTPH (2.1 g, 7.5 mmol) dissolved in 5 mL of toluene was added
dropwise to a stirred solution of Zr(NMe2)4 (1.01 g, 3.8 mmol) dissolved in 5 mL. The
solution was allowed to stir for 5 hours at reflux. The toluene was removed under vacuum
and the solid was recrystallized from pentane yielding orange-yellow crystals (1.6 g,
57.8%). mp 190 — 195 °C. 1H NMR (C5D6) 8 7.25 (br s, 2 H, C6H4CH3), 7.07 (mult, 2 H,
C6H4CH3), 6.87 (mult, 3 H, C6H4CH3), 5.67 (d, J = 3 Hz, 1 H, C6H4CH3), 5.13 (s, 1H,
CH3C(NAr)CHC(NAr)CH3), 2.64 (broad s, 6 H, N(CH3)2), 2.22 (s, 3 H, C6114CH3), 2.06
(s, 3 H, C6HaCH3) , 1.77 (s, 3 H, CH3C(NAr)CHC(NAr)CH3), 1.43 (s, 3 H,

CH3C(NAr)CHC(NAr)CH3). l3C{'H} NMR (C6116) 5 164.90, 164.33, 150.35, 149.99,

65

 

 

133.78, 133.07, 128.93, 128.47, 128.42, 127.20, 125.78, 100.50, 46.45, 25.81, 25.58,

20.96, 20.85. Anal.50 Calcd for C42H54N6Zr: C, 68.74; H, 7.36; N, 11.44. Found: c,
68.97; H, 7.35; N, 10.70.

(TP)2Zr(NMe2)2 (13). TPH (370 mg, 1.90 mmol) dissolved in 20 mL of pentane was
added dropwise to a stirred solution of Zr(NMe2)4 (260 mg, 0.97 mmol) dissolved in 2
mL of pentane at room temperature. Upon completion of the addition, a yellow solid
precipitated. The solid was allowed to settle and the solution was removed via cannula.
The solid was pure by 1H NMR, but could be recrystallized from pentane if necessary.
The volume of the filtrate was reduced under vacuum and placed in —80 °C freezer to
yield several more crops of yellow crystals (355mg, 66%). mp 164—166 °C. lH NMR
(C6D6) 8 6.97 (s, 2 H, C6H4CH3), 6.94 (s, 1 H, C6H4CH3), 6.66 (s, 1 H, C6H4CH3), 4.95
(s, 1 H, CH3C(O)CHC(NAr)CH3), 3.30 (s, 6 H, N(CH3)2), 2.16 (s, 3 H, C6H4CH3), 1.56
(s, 3 H, CH3 backbone), 1.42 (s, 3 H, CH3 backbone); l3C{'H} NMR (C6D6) 5 173.90, 168.91,
148.26, 133.19, 129.15, 128.87, 124.46, 123.41, 102.78, 44.56, 24.41, 23.39, 20.83;
Anal. Calcd for C23H40N402Zr: C, 60.50; H, 7.25; N, 10.08. Found: C, 60.0; H, 7.39; N,
9.90.

(DDP)ZrCl(NMe2)2 (14). A stirred suspension of DDPH(HCl) (430 mg, 0.94 mmol)
dissolved in 2 mL toluene was cooled to —78 °C. Zr(NMe2)4 (250 mg, 0.93 mmol)
dissolved in 2 mL of toluene was added dropwise to the cooled solution via cannula.
Once the addition was complete, the solution was allowed to warm to RT. All solids
dissolved leaving a clear green solution. The reaction mixture was allowed to stir
overnight. The toluene was removed under vacuum. The remaining solid was

recrystallized from pentane yielding small colorless crystals (300 mg, 51%). mp 197-199

66

 

 

 

°C. 1H NMR (cam) at 50 °c 5 7.12 (s. 6 H, C6H3(CH(CH3)2)2), 5.20 (s, 1 H,

CH3C(NAr)CHC(NAr)CH3), 3.03 (sept, J = 6.9 Hz, 4 H, C6H3(CH(CH3)2)2), 2.70 (s, 12
H, N(CH3)2), 1.63 (s, 6 H, CH3C(NAr)CHC(NAr)CH3), 1.37 (d, J = 6.8 Hz, 12 H,
C6H3(CH(CH3)2)2), 1.15 (d, J = 6.8, 12 H, C6H3(CH(CH3)2)2), 13(:(‘H} NMR (c613,) at
50 °C 8 167.02, 149.29, 141.69, 126.05, 123.90, 100.84, 41.73, 29.104, 25.95, 25.13,
24.27. Anal.50 Calcd for C33H53N4C1Zr: C, 62.58; H, 8.45; N, 8.85. Found: C, 62.50; H,
8.61; N, 8.62.

(TTP)Zr(NMe2)(p-NC5H4Me) (15). p-toluidine (69 mg, 0.64 mmol) was added dropwise
at RT to a stirred solution of (TTP)Zr(NMe2)3 (320 mg, 0.63 mmol) dissolved in 2 mL of
toluene The reaction mixture was allowed to stir for 6 hours. The solution volume was
reduced under vacuum. The yellow solid was washed with toluene and then pentane. Due
to poor solubility, recrystallization as well as collection of 13C NMR data has been
unsuccessful. (mp 210-213 °C). 1H NMR (CD6) 8 6.91 (d, J = 7.8 Hz, 6 H, aromatic)
6.74 (d, J = 8.1 Hz, 4 H, aromatic), 6.36 (d, J = 8.1 Hz, 2 H, aromatic), 5.30 (s, 1H,
CH3C(NAr)CHC(NAr)CH3), 2.78 (s, 6H, N(CH3)2), 2.26 (s, 3 H. NC61-14CH3), 2.11 (s, 6

H, C6H4CH3), 1.82 (s, 6 H, CH3C(NAr)CHC(NAr)CH3).

67

 

 

 

 

 

Appendix A: Bond Lengths and Angles

for

(”PhZI‘Clz (3)

(munch (4)

(DDP)ZrCl3 (5)
('ITP)Zr(CH2Ph)3 (8)
(TTP*)ZT(CH2Ph)2 (9)
(TTP)Zr(NMe2)3 (10)
(TTP)Ti(NM62)3 (11)
(TP)2Zr(NMe2)2 (13)

(DDP)ZIC1(NM62)2 (14)

68

 

Table 6 Selected Bond Lengths and Angles for 3,4 and 5

 

 

 

 

 

(TTP)2ZrCl2 (3) (T TP)TiCl3 (4) (DDP)ZrCl3 (5)
Bond Lengths (A)
Zr(1)-N(1) 2.243(2) Ti(1)-N(2) 1.995(4) Zr(1)-N(1)#1 2.202(2)
Zr(1)-N(2) 2.197(2) Ti(1)-N(1) 1.995(4) Zr(1)-N(1) 2.202(2)
Zr(1)-N(3) 2.214(2) Ti(1)-Cl(1) 2.218(2) Zr(1)-Cl(l) 2.3945(7)
Zr(1)-N(4) 2.272(2) Ti(1)-Cl(2) 2.337(2) Zr(1)-Cl(1)#1 2.3945(7)
Zr(1)-Cl(1) 2.4312(7) Ti(1)-C1(3) 2.335(2) Zr(l)-Cl(2) 2.3392(9)
Zr(1)-Cl(2) 2.4426(7) Ti(1)-C(4) 2.535(5)
Ti(1)-C(3) 2.535(4)
Ti(1)-C(2) 2.559(5)
Bond Angles (°)
N(2)—Zr(1)-N(3) 157.65(6) N(2)—Ti(1)-N(1) 85.1(2) N(1)#1-Zr(l)-N(l) 8364(8)
N(2)-Zr(1)—N(1) 79.31(7) N(2)-Ti(1)—Cl(1)95.38(12) N(1)#1-Zr(1)-Cl(2) 102.54(5)
N(3)-Zr(1)-N(1) 87.49(6) N(1)—Ti(1)-Cl(1)99.29(12) N(1)—Zr(1)-Cl(2) 102.54(5)
N(2)-Zr(1)—N(4) 8319(6) N(2)-Ti(l)-C1(3) 162.77(12)N(1)#1-Zr(1)-Cl(l) 149.45(5)
N(3)—Zr(l)—N(4) 78.52(6) N(1)-Ti(1)-Cl(3) 91.27(13) N(l)-Zr(l)—Cl(1) 86.97(4)
N(1)—Zr(l)—N(4) 88.72(6) Cl(l)—Ti(1)-Cl(3)101.83(6) Cl(2)-Zr(1)-Cl(1) 107.86(3)

N(2)-Zr(1)—Cl(1) 9964(5)
N(3)-Zr( 1 )—Cl( 1) 9767(5)
N(1)-Zr(l)-Cl(1) 8739(5)

N(2)—Ti(1)-Cl(2) 87.25(12) N(1)#l-Zr(1)—Cl(1)# 186.97(4)

N(l)-Ti(l)-Cl(2) 152.34(12)N(l)-Zr(1)—Cl(1)#l

149.46(5)

Cl( 1 )—Ti( 1 )-Cl(2) 107.87(6) Cl(2)-Zr( l)—Cl(1)#l 107.86(3)
N(4)-Zr(1)-Cl(1) l74.67(4) Cl(3)-Ti(1)-Cl(2) 8827(7) Cl(l)-Zr( 1)-Cl(1)#1 8654(4)
N(2)—Zr(1)—Cl(2) 9870(5)
N(3)—Zr( l )-Cl(2) 9528(5)
N(l)-Zr(1)-Cl(2) 176.51(5)
N(4)-Zr( l )-Cl(2) 9391(5)
Cl(1)—Zr(1)-Cl(2) 9013(3)

69

 

 

 

Vi - ;r-r-w ‘
. «‘1 ; -_-. § ‘-
I "' ' '. J

 

 

 

Table 7 Selected Bond Lengths and Angles for 8 and 9

 

 

 

 

 

(TTP)Zr(CH2Ph)3 (8) (TTP*)Zr(CH2Ph)2 (9)
Bond lengths (A)
Zr(1)—N(2) 2.189(2) Zr(1)-N(1) 2.175(2)
Zr(1)-N(1) 2.205(2) Zr(1)-N(2) 2.253(2)
Zr(1)—C(20) 2.253(3) Zr(1)—C(14) 2.260(2)
Zr(1)-C(27) 2.304(3) Zr(1)-C(27) 2.288(2)
Zr(1)—C(34) 2.313(3) Zr(1)—C(20) 2.302(2)
Zr(1)-C(21) 2.584(2)
Zr(1)-C(13) 2.781(2)
Bond Angles (°)
N(2)—Zr(1)-N(1) 7651(8) N(l)-Zr(l)-N(2) 7791(6)
N(2)-Zr(1)-C(20) 111.35(11) N(1)—Zr(1)-C(14) 138.48(6)
N(1)—Zr(1)-C(20) 112.51(10) N(2)-Zr(1)-C(14) 6063(7)
N(2)—Zr(1)-C(27) 8479(9) N(1)-Zr(1)—C(27) 100.45(7)
N(1)-Zr(1)-C(27) 133.30(9) N(2)-Zr(1)-C(27) 114.65(6)
C(20)—Zr(1)-C(27) 114.13(11) C(14)-Zr(1)-C(27) 9865(7)
N(2)-Zr(1)-C(34) 139.09(10) N(1)-Zr(1)-C(20) 9892(7)
N(1)—Zr(1)-C(34) 81.81(10) N(2)-Zr(1)-C(20) 116.16(6)
C(20)-Zr(l)—C(34) 108.90(12) C(14)-Zr(l)-C(20) 9754(7)
C(27)-Zr(1)-C(34) 85.48(11) C(27)-Zr(1)-C(20) 128.25(7)
C(21)—C(20)—Zr(1) 99.1(2) N(1)-Zr(1)-C(21) 113.00(6)
C(28)—C(27)—Zr(1) 117.6(2) N(2)-Zr(1)-C(21) 147.23(6)
C(35)—C(34)-Zr(1) 110.7(2) C(14)-Zr(1)-C(21) 101.84(7)
C(27)-Zr(1)-C(21) 9432(6)
C(20)-Zr(1)-C(21) 34.13(6)
N(1)-Zr(1)-C(13) 108.35(6)
N(2)—Zr(1)-C(13) 3056(5)
C(14)-Zr(l)-C(13) 3013(6)
C(27)-Zr(l)-C(13) 110.53(6)
C(20)-Zr(1)-C(13) 107.90(7)
C(21)—Zr(1)-C(13) 126.22(6)
C(21)—C(20)-Zr(1) 83.58(11)
C(28)-C(27)-Zr(1) 99.64(11)

70

 

 

 

     

 

 

Table 8 Selected Bond Lengths and Angles for 10 and 11

 

 

 

 

 

(TTP)Zr(NMe2)3 (10) (TTP)Ti(NMe2)3 (11)
Bond Lengths (A)
Zr(l)-N(3) 2.019(4) Ti(1)-N(4) 1.9102(13)
Zr(1)-N(4) 2.031(4) Ti(l)-N(5) 1.9180(13)
Zr(1)-N(5) 2.071(4) Ti(l)-N(3) 1.9592(13)
Zr(1)-N(2) 2.211(4) Ti(1)-N(l) 2.0900(12)
Zr(1)-N(l) 2.350(4) Ti(1)-N(2) 2.2371(13)
Bond Angles (°)

N(3)—Zr(1)—N(4) 120.5(2) N(4)-Ti(l)-N(5) 121.34(6)
N(3)-Zr(l)-N(5) 94.5(2) N(4)-Ti(1)-N(3) 9271(6)
N(4)-Zr(1)-N(5) 91.6(2) N(5)-Ti(l)-N(3) 9149(6)
N(3)-Zr(1)-N(2) 118.4(2) N(4)—Ti(1)-N(1) 119.35(6)
N(4)-Zr(1)-N(2) 119.8(2) N(5)-Ti(1)-N(l) 118.34(5)
N(5)-Zr(1)-N(2) 95.0(2) N(3)-Ti(1)-N(l) 9565(5)
N(3)-Zr(1)-N(1) 92.3(2) N(4)-Ti(l)-N(2) 8948(6)
N(4)-Zr(1)-N(1) 88.2(2) N(5)-Ti(1)-N(2) 8829(5)
N(5)-Zr(1)-N(1) 172.13(14) N(3)-Ti(1)-N(2) 177.56(5)
N(2)-Zr(1)-N(1) 78.28(14) N(1)-Ti(1)-N(2) 8232(5)
C(20)-N(3)-C(21) 112.0(5) C(21)-N(3)-C(20) 108.9(2)
C(20)-N(3)-Zr(1) 126.5(4) C(21)-N(3)-Ti(l) 124.9503)
C(21)-N(3)-Zr(1) 121.3(4) C(20)-N(3)-Ti(l) 125.17(12)
C(22)-N(4)-C(23) 113.8(5) C(23)—N(4)-C(22) 112.2(2)
C(22)-N(4)-Zr(1) 132.0(4) C(23)-N(4)-Ti(l) 123.55(14)
C(23)-N(4)-Zr(l) 114.1(4) C(22)—N(4)-Ti(1) 124.3(2)
C(24)-N(5)-C(25) 107.6(4) C(24)-N(5)-C(25) 112.4(2)
C(24)-N(5)-Zr(l) 127.9(3) C(24)-N(5)-Ti(1) 129.4(2)
C(25)—N(5)-Zr(1) 123.8(3) C(25)-N(5)-Ti(1) 118.09(12)

71

 

 

 

 

 

 

Table 9 Selected Bond Lengths and Angles for 13

 

 

(TP)2Zr(NMe2)2 (13)
Bond Lengths (A)

 

Zr(1)-0(2)
Zr(1)-0( 1)
Zr(1)-N(4)
Zr(1)-N(3)
Zr( 1 )-N( l)
Zr(1)-N(2)

2.050(4)
2.051(4)
2.077(5)
2.076(5)
2.385(5)
2.400(5)

 

0(2)-Zr(1)-0(1)
O(2)—Zr( 1 )-N(4)
0(1)-Zr(l)-N(4)
0(2)-Zr(1)-N(3)
0(1)-Zr(l)-N(3)
N(4)-Zr(1)-N(3)
0(2)-Zr(1)-N( 1)
0( 1 )-Zr( 1 )-N( 1)
N(4)-Zr(1)-N(1)
N(3)-Zr(1)-N( 1)
0(2)-Zr(1)-N(2)
O( 1 )-Zr( 1 )—N(2)
N(4)-Zr(1)-N(2)
N(3)-Zr(1)-N(2)
N( 1 )-Zr( 1 )—N(2)

C(26)—N(3)—C(25)

C(26)-N(3)-Zr(1)
C(25)-N(3)—Zr( 1)

C(27)-N(4)-C(28)

C(27)—N(4)-Zr( l)
C(28)—N(4)-Zr( 1)

Bond Angles (°)

72

164.0(2)
95.7(2)
94.7(2)
94.5(2)
94.6(2)
104.4(2)
90.7(2)
76.4(2)
164.7(2)
88.9(2)
77.0(2)
91 .6(2)
86.3(2)
167.1(2)
81 .6(2)
109.7(5)
123.0(4)
126.9(4)
1 10.0(5)
125.0(4)
124.2(4)

 

 

 

 

 

 

 

Table 10 Selected Bond Lengths and Angles for 14

 

 

 

 

 

 

(DDP)ZrCl(NMe2)2 #1 (14) (DDP)ZrCl(NMe2)2 #2
Bond Lengths (A)
Zr(1)-N(4) 2.014(2) Zr(11)—N(13) 2.014(2)
Zr(1)-N(3) 2.052(2) Zr(11)—N(14) 2.066(2)
Zr(1)-N(2) 2.249(2) Zr(11)-N(11) 2.258(2)
Zr(1)-N(l) 2.319(2) Zr(11)—N(12) 2.328(2)
Zr(1)-Cl(1) 2.4776(8) Zr(11)-Cl(11) 2.4979(8)
Bond Angles (°)
N(4)—Zr(1)-N(3) 107.28(11) N(13)-Zr(11)—N(14) 107.66(10)
N(4)-Zr(1)-N(2) 101.97(9) N(13)-Zr(11)-N(11) 101.52(9)
N(3)-Zr(1)-N(2) 9392(9) N(14)-Zr(11)-N(11) 9201(9)
N(4)-Zr(1)—N(1) 103.77(9) N(13)-Zr(11)-N(12) 101.56(9)
N(3)-Zr(1)—N(1) 148.9400) N(14)-Zr(11)-N(12) 150.75(9)
N(2)-Zr(1)—N(l) 8061(8) N(11)-Zr(11)-N(12) 8060(8)
N(4)-Zr(1)-Cl(1) 10461(7) N(13)—Zr(1 1)-C1(1 1) 107.71(8)
N(3)-Zr(1)-Cl(1) 8657(8) N(14)-Zr(ll)-C1(11) 8765(7)
N(2)—Zr(1)—Cl(1) 151.99(6) N(11)-Zr(11)-Cl(11) 149.42(6)
N(1)-Zr(1)-Cl(1) 8463(6) N(12)-Zr(11)-Cl(11) 8488(6)
C(30)—N(3)—C(31) 110.7(3) C(133)-N(13)-C(132) 112.5(3)
C(30)—N(3)—Zr(1) 128.8(2) C(133)-N(13)-Zr(11) 125.5(2)
C(31)-N(3)-Zr(1) 120.3(2) C(132)—N(13)—Zr(1 1) 121.8(2)
C(33)—N(4)-C(32) 111.8(3) C(130)-N(14)-C(13 1) 111.6(3)
C(33)-N(4)-Zr(1) 124.5(2) C(130)-N(14)-Zr(11) 1 16.5(2)
C(32)—N(4)—Zr(1) 123.5(2) C(131)-N(14)-Zr(11) 131.9(2)

73

 

 

Appendix B: Single Crystal X-ray Structure Key Data Collection and [

Refinement Parameters

(TTP»Zbe (3)

(TTP)TiCl3 (4)

(DDP)ZrCl3 (5)
(TTP)Zr(CH2Ph)3 (8)
(TTP*)ZI(CH2Ph)2 (9)
('ITP)Zr(NMe2)3 (10)
(ITP)Ti(NMe2)s (11)
(TP)2Zr(NMe2)2 (13)

(DDP)ZrCl(NMe2)2 (14)

74

 

Table 11 Key X-ray Parameters, Refinement and Results for 3, 4 and 5

Empirical formula
Formula weight
Temperature (K)
Wavelength (A)
Crystal system
Space group

Cell

a (A)

b (A)

c (A)

01 (°)

B (°)

x (°)

Volume (A3)

Z

d (calc.) (Mg/m3)
Abs. coef. hum")
F (000)

Crystal size (mm)
20 range (°)
Index ranges

Reflections collected
Independent reflections

Refinement method
Data / restraints /
parameters

GOF / F2

Final R indices [I>26(I)]
R indices (all data)

Largest diff. peak and
hole (e A'3)

(TTP)erClz (3)
C38H42C12N4Zr
716.88

173(2)

0.71073
Monoclinic

P2 {/11

9.179(2)
22.868(5)
16.813(3)
90
9877(3)
90
3487.902)
4

1.365
0.501

1488
0.2 x 0.2 x 0.25
1.51 to 28.39

-10 <= h <= 12
—27 <= k <= 30
-22 <= 1 <= 21
21485

8272 [R(int) =
0.0318]
Full-matrix least-
squares on F2
8272 / 0 / 574

1.019

R1 = 0.0348, wR2
= 0.0706

R1 = 0.0571, wR2
= 0.0770

274 and -0.551

(T TP)TiCl3 (4)

C19H21C13N2T1(C7H8)

503.69
173(2)
0.71073
Triclinic
PT

7.286(2)
13.154(3)
15.253(3)
103.25(3)
9996(3)
9458(3)
1390.6(5)
2

1.203
0.609

516
0.2 x 0.2 x 0.25
1.60 to 28.29

-9 <= h <= 9

-17 <= k <= 17
-13 <= 1 <=20
8178

5865 [R(int) =
0.0903]
Full-matrix least-
squares on

5865 / 33 / 343

0.846

R1 = 0.0795, wR2 =
0.1877

R1 = 0.1278, wR2 =
0.2027

0.495 and -l.076

(DDP)ZrCl3 (5)
C29H41C13N22r
615.21

173(2)

0.71073
Orthorhombic
ana

14.054(3)
21.842(4)
9.856(2)
90

90

90
3025.6(11)
4

1.351
0.648

1280
0.2 x 0.1 x 0.06
1.86 to 28.32

-18 <= h <=18
-28 <= k <=29
-12 <= 1 <= 12
33445

3804 [R(int) =
0.0437]
Full-matrix least-
squares on
3804/ O/ 175

0.859

R1 = 0.0345, wR2
= 0.1032

R1 = 0.0493, wR2
= 0.1144

0.393 and —0.591

 

 

 

 

 

 

 

Table 12 Key X-ray ParameterS, RBfinement and Results for 8 and 9

Empirical formula
Formula weight
Temperature (K)
Wavelength (A)
Crystal system

Space group
Cell

a (A)

b (A)

c (A)

01(°)

B (°)

x (°)

Volume (A3)

Z

d (calc.) (Mg/m3)
Abs. Coef. (mm'l)
F(000)

Crystal size (mm)
20 range (°)
Index ranges

Reflections collected
Independent reflections
Refinement method

Data / restraints /
parameters

GOF / F“

Final R indices [I>20'(I)]

R indices (all data)

Largest diff. peak and
hole (e A'3)

(TTP)Zr(CH2Ph)3 (8)
C40H47N2Zr

647.02

173(2)

0.71073

Monoclinic

C2/c

40.287(8)
9.191(2)
20.566(4)
90

1 1727(3)
90
6769(2)

8

1.270

0.354

2728

0.2 x 0.2 x 0.2
1.98 to 28.40

-53 <= h <= 39

-1 1 <= k <= 12

-25 <= 1 <= 26

19559

7797 [R(int) = 0.0504]
Full-matrix least-
squares on

7796 / 0 / 556

1.000

R1 = 0.0446, wR2 =
0.0822

R1: 0.0811, wR2 =
0.0939

0.345 and -0.635

76

(TTP*)Zr(CH2Ph)2 (9)
C33H34N2Zr

549.84

173(2)

0.71073

Triclinic

P T

10.167(2)
1 1.547(2)
13.192(3)
87.81(3)
7259(3)
6906(3)
1376.0(5)
2

1.327

0.423

572

0.2 x 0.2 x 0.25
1.62 to 28.32

 

-13 <= h <= 13

-15 <= k <= 14

-17 <= 1 <= 17

16390

6494 [R(int) = 0.0300]
Full-matrix least-
squares on

6494 / 459 / 409

 

1.009

R1 = 0.0305, wR2 =
0.0708

R1 = 0.0416, wR2 =
0.0741

0.265 and —0.444

 

 

 

Table 13 Key X-ray Parameters, Refinement and Results for 10, 11 and 13

Empirical formula
Formula weight
Temperature (K)
Wavelength (A)
Crystal system
Space group

Cell

a (A)

b (A)

c (A)

9 (°)

B (°)

x (°)

Volume (A3)

Z

d (calc.) (Mg/m3)
Abs. coef. (mm‘)
F (000)

Crystal size (mm)
20 range (°)
Index ranges

Reflections collected
Independent reflections

Refinement method
Data / restraints /
parameters

GOF/ re

Final R indices [I>2o(I)]
R indices (all data)

largest diff. peak and
hole (e A'3)

(TTP)Zr(NMez)3
(10)

C25H39N52r
500.83
173(2)
0.71073
Triclinic
PT

8.669(2)
10.385(2)
15.874(3)
102.19(3)
9292(3)
101.28(3)
1363.5(5)
2

1.220
0.422

528
0.20 x 0.20 x 0.25
2.05 to 28.34

-11 <= h <= 11
-13 <= k <= 13
-19 <= 1 <= 20
11671

6153 [R(int) =
0.0905]
Full-matrix least-
squares on

6153 /0 / 280

0.300

R1 = 0.0575, wR2 =
0.1382

R1 = 0.0969, wR2 =
0.1527

0.379 and —0.608

77

(TTP)Ti(NMe2)3
(11)
C25H39N3Ti
457.51
173(2)
0.71073
Triclinic
PT

8.69720(10)
10.51620(10)
15.53630(10)
102.53

93.59
102.5190(10)
l345.12(2)

2

1.130

0.337

492
0.2 x 0.2 x 0.15
1.35 to 28.23

-11 <= h <= 11
-13 <= k <= 13
-20 <= 1 <= 20
13940

6100 [R(int) =
0.0196]
Full-mauix least-
squares on

6100 / 0 / 436

0.921

R1 = 0.0359, wR2 =
0.1121

R1 = 0.0466, wR2 =
0.1205

0.254 and —0.327

(TP)2ZI‘(NM02)2
(13)

C28H40N4ozzf
555.86

173(2)
0.71073
Monoclinic
P21/C

18.272(4)
9.102(2)
l7.200(3)

98.15(3)

2831.5(1)
4

1.304
0.418

1168
0.24 x 0.22 x 0.20
2.25 to 28.34

-23 _<_ h S 23

5 S k S 12

20 S l S 22

14661

6399 [R(int) = 0.0752]

Full—matrix least-
squares on F"2

6399/0 I 316

0.987

R1 = 0.0771
wR2 = 0.1613
R1 = 0.1500
wR2 = 0.1958

0.496 and -0.652

 

 

Empirical formula
Formula weight
Temperature (K)
Wavelength (A)
Crystal system
Space group

Cell

a (A)

b (A)

c (A)

01 (°)

B (°)

x (°)

Volume (A3)

Z

d (calc.) (Mg/m3)
Abs. coef. (mm‘l)
F (000)

Crystal size (mm)
20 range (°)
Index ranges

Reflections collected

Independent reflections

Refinement method

Data / restraints /
parameters
GOF / Fa

Final R indices [I>26(I)]

R indices (all data)

Largest diff. peak and
hole (e A'3)

 

Table 14 Key X-ray Parameters, Refinement and Results for 14
(DDP)ZrCl(NMe2)2
(14)

[C33H53C1N4Zf12
1264.93

173(2)

0.71073
Triclinic

PT

12.3 1060( 10)
16.8085(3)
l7.5560(3)
87.0030(10)
76.07
77.9970( 10)
3448.82(9)

2

1.218

0.422

1344
0.18 x 0.15 x 0.08
1.72 to 28.30

~16 <= h <= 12
-22 <= k <= 21
-23 <= 1 <= 22
25293

15168 [R(int) =
0.0293]
Full-matrix least-
squares on

15168 / O / 703

0.836

R1 = 0.0424, wR2 =
0.1138

R1 = 0.0696, wR2 =
0.1314

0.503 and -0.506

 

 

11.

12.

 

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