THE ETHENE POLYMERISATION BEHAVIOUR OF 
ZIRCONIUM METALLOCENES: A STERIC AND 
ELECTRONIC INVESTIGATION INTO THE INFLUENCE OF 
SUBSTITUENT EFFECTS. 
 
 
Neil Eugene Grimmer 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in 
fulfilment of the requirements for the degree of Doctor of Philosophy 
Johannesburg, 2000 
 ii
 DECLARATION 
 
I hereby declare that this thesis is my own, unaided work, performed under the supervision of 
Professor N.J. Coville and Doctor C.B. de Koning.  It is being submitted for the Degree of Doctor of 
Philosophy in the University of the Witwatersrand, Johannesburg.  It has not been submitted before 
for any degree or examination in any other University. 
 
 
 
Neil Eugene Grimmer 
28th Day of March 2000 
 iii
 ABSTRACT 
 
A systematic investigation into the effect that alkyl and aryl substituents have on the ethene 
polymerisation behaviour of a series of MAO co-catalysed mono-substituted bis-
 (cyclopentadienyl)zirconium dichloride and bis-(indenyl)zirconium dichloride metallocenes was 
carried out.  The electronic attributes of the substituents were related to the Hammett substituent 
functions.  The sizes of the ligands were measured from the perspective of the metal using the 
Tolman cone angle, numerical solid angle and analytical solid angle methodologies.  For the mono-
 substituted cyclopentadienyl metallocenes of formula (CpR)2ZrCl2 (R = Me, Et, iPr, tBu, SiMe3, 
CMe2Ph), it was found that an optimum ligand size (R = Et, iPr) was required for high activity.  
These substituents protected the active polymerisation site from deactivation processes. However, if 
the substituent was too bulky (R = tBu, CMe2Ph) activity dropped drastically.  Electronic factors 
possibly also play a role as demonstrated by the much higher activity of the SiMe3 substituted catalyst 
over its similarly sized tBu analogue.  A series of new bis-(indenyl)zirconium dichloride metallocenes 
of formula [2?R-Ind]2ZrCl2 (R = H, Me, SiMe3, Ph, Bz and 1-Naphthyl) and [1?R-Ind]2ZrCl2 (R = 
Me, Et, iPr, tBu, SiMe3, Ph, Bz and 1-Naphthyl) were synthesised.  Ethene polymerisation reactions 
with these metallocenes revealed the same electronic and steric trends observed for the (CpR)2ZrCl2 
catalysts.  Steric effects were found to play an important role with polymerisation activity decreasing 
as the size of the substituent increases.  Also, the 1-substituted metallocenes had higher activities than 
their 2-substituted analogues, the differences in their activity increasing with the size of the 
substituent.  By studying the conformations adopted by the indenyl ligands in the solid state, we have 
rationalised this phenomenon to be a result of the greater steric protection afforded to the active 
polymerisation site by the 1-substituted metallocenes. 
 iv
 ACKNOWLEDGEMENTS 
 
This thesis would not have been possible without the input and support of a number of people to who 
I am gratefully indebted.  This page gives me the opportunity to thank these important people. 
? My two supervisors, Prof. N.J. Coville and Dr C.B. de Koning, for providing me with the 
opportunity to work under their expert guidance.  It is a privilege for which I am tremendously 
grateful.  The challenges presented to me would not have been surmounted without their 
knowledge, support and unhealthy optimism, the latter which at times may have required 
observation by white-coats of a different nature! 
? My wonderful parents, who despite being cursed with an ungrateful son, always find reasons to 
provide more love and support.  I am truly blessed. 
? My beautiful sister, for reasons too many to mention here. 
? The unique collection of hooligans and persons of ill repute who happen to be my friends. 
Without your insanity, I would most certainly have lost mine.  Thanks for standing by me all 
these years and understanding all the times I could not ?come out and play?. 
? Apologies to Tshepo Malefetse, Bhekie Mamba, Namadzavho Sitabule, Miranda Mamabolo and 
Jeremy Smith who had the misfortune of sharing the laboratory with this difficult mlungu for the 
longest period of time.  Thank you for all the wonderful lessons, discussions and laughs.  Not 
only should we be running this country, but more importantly, the national football team too!  It 
will be a tremendous honour to be considered as not just a colleague, but a friend as well. 
? Jeremy Smith and Leanne Cook for all the help with the two crystal structures.  During the dark 
months leading to the conclusion of this project, my frayed personality was in no position to deal 
directly with the quirks of difficult structures and refinement routines. 
? All the technical staff, without whose help none of this work would have been possible.  Barry 
Fairbrother and Stephen Gannon, for their adroit glass-blowing talents.  Sigi Heiss for her 
friendly NMR spectroscopy service.  Basil Chassoulas for electronics and the long-suffering 
Physics workshop for helping me to get my polymerisation reactor working smoothly. 
 v
 CONTENTS 
 
DECLARATION....................................................................................................................................II 
ABSTRACT.......................................................................................................................................... III 
ACKNOWLEDGEMENTS ................................................................................................................ IV 
CONTENTS............................................................................................................................................V 
LIST OF FIGURES...............................................................................................................................X 
LIST OF SCHEMES ........................................................................................................................ XIV 
LIST OF TABLES...........................................................................................................................XVII 
ABBREVIATIONS........................................................................................................................... XIX 
GLOSSARY......................................................................................................................................XXII 
CHAPTER 1: INTRODUCTION ...................................... ERROR! BOOKMARK NOT DEFINED. 
CHAPTER 2: LITERATURE SURVEY ? A REVIEW OF CYCLOPENTADIENYL TYPE 
LIGANDS IN GROUP 4 METALLOCENE OLEFIN-POLYMERISATION CATALYSTS.
 ................................................................................................ ERROR! BOOKMARK NOT DEFINED. 
2.1. INTRODUCTION AND HISTORICAL PERSPECTIVE............. ERROR! BOOKMARK NOT DEFINED. 
2.2. THE NATURE OF METALLOCENE CATALYSTS................. ERROR! BOOKMARK NOT DEFINED. 
2.2.1. The active polymerisation species................................... Error! Bookmark not defined. 
2.2.2. Polymerisation mechanism.............................................. Error! Bookmark not defined. 
2.2.2.1.  Monomer insertion and chain growth...........................................Error! Bookmark not defined. 
2.2.2.2.  Chain transfer mechanisms...........................................................Error! Bookmark not defined. 
2.3. THE DESIGN OF METALLOCENE, OLEFIN POLYMERISATION CATALYSTSERROR! BOOKMARK 
NOT DEFINED. 
2.3.1. The effect of metal on polymerisation results ................. Error! Bookmark not defined. 
 vi
 2.3.2. The cyclopentadienyl ligand............................................ Error! Bookmark not defined. 
2.3.3. Metallocene symmetry and polymer tacticity ................. Error! Bookmark not defined. 
2.3.4. The effect of ring substituents.......................................... Error! Bookmark not defined. 
2.3.4.1. Unbridged metallocenes ...........................................................Error! Bookmark not defined. 
2.3.4.2. Bridged metallocenes................................................................Error! Bookmark not defined. 
2.3.4.3. The effect of bridge choice .......................................................Error! Bookmark not defined. 
2.3.5. Metallocene synthesis: resolving the problem of diastereomers...Error! Bookmark not 
defined. 
2.3.5.1. Synthetic strategies ...................................................................Error! Bookmark not defined. 
2.3.5.2. Ligand strategies .......................................................................Error! Bookmark not defined. 
2.3.5.3. Separation strategies .................................................................Error! Bookmark not defined. 
2.4. CONCLUSIONS ................................................................. ERROR! BOOKMARK NOT DEFINED. 
2.5. TABLES OF POLYMERISATION DATA............................... ERROR! BOOKMARK NOT DEFINED. 
2.6. REFERENCES.................................................................... ERROR! BOOKMARK NOT DEFINED. 
CHAPTER 3: GENERAL EXPERIMENTAL PROCEDURES .......ERROR! BOOKMARK NOT 
DEFINED. 
3.1. INTRODUCTION ................................................................ ERROR! BOOKMARK NOT DEFINED. 
3.2. EXPERIMENTAL PROCEDURES ......................................... ERROR! BOOKMARK NOT DEFINED. 
3.2.1. Purification of solvents.................................................... Error! Bookmark not defined. 
3.2.2. Laboratory bench set-up ................................................. Error! Bookmark not defined. 
3.2.3. Experimental techniques ................................................. Error! Bookmark not defined. 
3.3. CHARACTERISATION PROCEDURES ................................. ERROR! BOOKMARK NOT DEFINED. 
3.3.1. NMR spectroscopy........................................................... Error! Bookmark not defined. 
3.3.2. X-ray crystal diffractometry ............................................ Error! Bookmark not defined. 
3.3.3. Mass Spectrometry .......................................................... Error! Bookmark not defined. 
3.3.4. Elemental analysis........................................................... Error! Bookmark not defined. 
3.3.5. Differential scanning calorimetry (DSC)........................ Error! Bookmark not defined. 
3.4. POLYMERISATION STUDIES ............................................. ERROR! BOOKMARK NOT DEFINED. 
3.4.1. Polymerisation reactor and rig design ........................... Error! Bookmark not defined. 
3.4.2. Polymerisation Reaction Details..................................... Error! Bookmark not defined. 
 vii
 3.4.2.1. Co-catalyst preparation .............................................................Error! Bookmark not defined. 
3.4.2.2. Polymerisation procedures........................................................Error! Bookmark not defined. 
3.4.2.3. Polymer Processing...................................................................Error! Bookmark not defined. 
3.5. REFERENCES.................................................................... ERROR! BOOKMARK NOT DEFINED. 
CHAPTER 4: QUANTIFICATION OF STERIC EFFECTS IN GROUP 4 METALLOCENES
 ................................................................................................ ERROR! BOOKMARK NOT DEFINED. 
4.1. INTRODUCTION ................................................................ ERROR! BOOKMARK NOT DEFINED. 
4.1.1. Cone Angle Measurements, ?.......................................... Error! Bookmark not defined. 
4.1.2. Solid Angle Measurements, ?. ........................................ Error! Bookmark not defined. 
4.1.3. Summary .......................................................................... Error! Bookmark not defined. 
4.1.4. Steric Measurement of Cyclopentadienyl Ligands ......... Error! Bookmark not defined. 
4.1.5. Aims.................................................................................. Error! Bookmark not defined. 
4.2. METHODS SECTION ......................................................... ERROR! BOOKMARK NOT DEFINED. 
4.3. RESULTS AND DISCUSSION.............................................. ERROR! BOOKMARK NOT DEFINED. 
4.3.1. Crystal Structure Analysis............................................... Error! Bookmark not defined. 
4.3.2. A comparative analysis of the C5H5R ligand size ........... Error! Bookmark not defined. 
4.3.3. Analysis of the Co-ordination Gap Aperture.................. Error! Bookmark not defined. 
4.4. CONCLUSIONS ................................................................. ERROR! BOOKMARK NOT DEFINED. 
4.5. REFERENCES.................................................................... ERROR! BOOKMARK NOT DEFINED. 
CHAPTER 5: A STUDY OF STERIC AND ELECTRONIC PARAMETERS: THEIR 
INFLUENCE ON THE ETHENE POLYMERISATION ACTIVITY FOR A SET OF 
(CPR)2ZRCL2/MAO CATALYSTS................................... ERROR! BOOKMARK NOT DEFINED. 
5.1. INTRODUCTION ................................................................ ERROR! BOOKMARK NOT DEFINED. 
5.2. EXPERIMENTAL ............................................................... ERROR! BOOKMARK NOT DEFINED. 
5.2.1. General Experimental Methods ...................................... Error! Bookmark not defined. 
5.2.2. Synthesis of the (CpR)2ZrCl2 metallocenes..................... Error! Bookmark not defined. 
5.2.3. Ethene polymerisation reactions..................................... Error! Bookmark not defined. 
5.2.4. Steric measurements........................................................ Error! Bookmark not defined. 
5.3. RESULTS AND DISCUSSION.............................................. ERROR! BOOKMARK NOT DEFINED. 
 viii
 5.3.1. (CpR) Steric and Electronic parameters......................... Error! Bookmark not defined. 
5.3.2. Polymerisation studies .................................................... Error! Bookmark not defined. 
5.4. CONCLUSIONS ................................................................. ERROR! BOOKMARK NOT DEFINED. 
5.5. REFERENCES.................................................................... ERROR! BOOKMARK NOT DEFINED. 
CHAPTER 6: SYNTHESIS OF A SERIES OF BIS-(INDENYL)ZIRCONIUM DICHLORIDE 
METALLOCENES:  SUBSTITUTION BY ALKYL AND ARYL GROUPS AT THE 1- AND 2-
 INDENYL RING POSITIONS........................................... ERROR! BOOKMARK NOT DEFINED. 
6.1. INTRODUCTION ................................................................ ERROR! BOOKMARK NOT DEFINED. 
6.2. EXPERIMENTAL SECTION ................................................ ERROR! BOOKMARK NOT DEFINED. 
6.2.1. General Experimental Procedures.................................. Error! Bookmark not defined. 
6.2.2. Synthesis of the substituted indene ligands..................... Error! Bookmark not defined. 
6.2.3. Synthesis of the bis-(R-indenyl)zirconium dichloride metallocenes ...Error! Bookmark 
not defined. 
6.3. RESULTS AND DISCUSSION.............................................. ERROR! BOOKMARK NOT DEFINED. 
6.3.1. Synthesis of the substituted indene ligands..................... Error! Bookmark not defined. 
6.3.1.1. 1- and 3-Substituted indenes.....................................................Error! Bookmark not defined. 
6.3.1.2. 2-Substituted indenes ................................................................Error! Bookmark not defined. 
6.3.2. Synthesis of the bis-(R-indenyl)zirconium dichloride complexes..Error! Bookmark not 
defined. 
6.4. CONCLUSIONS ................................................................. ERROR! BOOKMARK NOT DEFINED. 
6.5. REFERENCES.................................................................... ERROR! BOOKMARK NOT DEFINED. 
CHAPTER 7: A CRYSTALLOGRAPHIC AND STERIC STUDY OF BIS-
 (INDENYL)ZIRCONIUM DICHLORIDE COMPOUNDS...............ERROR! BOOKMARK NOT 
DEFINED. 
7.1. INTRODUCTION ................................................................ ERROR! BOOKMARK NOT DEFINED. 
7.2. METHODS SECTION ......................................................... ERROR! BOOKMARK NOT DEFINED. 
7.2.1. Crystallographic procedures........................................... Error! Bookmark not defined. 
7.2.2. Steric measurement procedures ...................................... Error! Bookmark not defined. 
7.3. RESULTS AND DISCUSSION.............................................. ERROR! BOOKMARK NOT DEFINED. 
7.3.1. Crystallographic studies.................................................. Error! Bookmark not defined. 
 ix
 7.3.2. Quantification of steric effects ........................................ Error! Bookmark not defined. 
7.4. CONCLUSIONS ................................................................. ERROR! BOOKMARK NOT DEFINED. 
7.5. REFERENCES.................................................................... ERROR! BOOKMARK NOT DEFINED. 
CHAPTER 8: A STUDY OF THE ETHENE POLYMERISATION BEHAVIOUR OF A SET 
OF 1- AND 2-SUBSTITUTED BIS-(INDENYL)ZIRCONIUM DICHLORIDE 
METALLOCENES.............................................................. ERROR! BOOKMARK NOT DEFINED. 
8.1. INTRODUCTION ................................................................ ERROR! BOOKMARK NOT DEFINED. 
8.2. EXPERIMENTAL SECTION ................................................ ERROR! BOOKMARK NOT DEFINED. 
8.2.1. General experimental methods........................................ Error! Bookmark not defined. 
8.2.2. Ethene polymerisation reactions..................................... Error! Bookmark not defined. 
8.2.3. Steric measurements........................................................ Error! Bookmark not defined. 
8.3. RESULTS AND DISCUSSION.............................................. ERROR! BOOKMARK NOT DEFINED. 
8.3.1. Assessment of steric and electronic parameters ............. Error! Bookmark not defined. 
8.3.2. Polymerisation reactions................................................. Error! Bookmark not defined. 
8.4. CONCLUSIONS ................................................................. ERROR! BOOKMARK NOT DEFINED. 
8.5. REFERENCES.................................................................... ERROR! BOOKMARK NOT DEFINED. 
CHAPTER 9: SUMMARY AND CONCLUSIONS ........ ERROR! BOOKMARK NOT DEFINED. 
APPENDIX A: INDEX TO CD-ROM............................... ERROR! BOOKMARK NOT DEFINED. 
A1.  Crystallographic Data ............................................................. Error! Bookmark not defined. 
A2.  Thesis ........................................................................................ Error! Bookmark not defined. 
A3.  Steric......................................................................................... Error! Bookmark not defined. 
 
 x
 LIST OF FIGURES 
 
Figure 2.1.  A constrained geometry catalyst. ........................ Error! Bookmark not defined. 
Figure 2.2.  Examples of the cyclopentadienyl family of ligands.Error! Bookmark not 
defined. 
Figure 2.3.  The substituent on the monomer units in the polymer chain can be positioned in 
different orientations to each other giving rise to different stereostructures. .......... Error! 
Bookmark not defined. 
Figure 2.4.  The last inserted unit in a chain end controlled catalysts (a) defines the 
orientation of the next inserted unit whereas for a catalytic-site controlled catalyst (b), 
any errors are corrected by the chirality of the catalyst. .. Error! Bookmark not defined. 
Figure 2.5.  For olefin polymerisation reactions, metallocenes may be divided in to four main 
point-groups, examples of each are shown here. ........... Error! Bookmark not defined. 
Figure 2.6.  The growing polymer chain always occupies the least congested quadrant.  Non 
bonded interactions with the chain forces a trans orientation of the monomer R-group.
 .......................................................................................Error! Bookmark not defined. 
Figure 2.7.  Depiction of the substituents on the ?- and ?-positions on the cyclopentadienyl, 
indenyl and fluorenyl ring moieties..................................Error! Bookmark not defined. 
Figure 2.8.  Three main bridging systems exist in ansa-metallocenes, namely ethyl, 
isopropyl and dimethylsilyl bridges. ................................Error! Bookmark not defined. 
Figure 2.9.  The use of chiral ligands in the synthesis of ansa-metallocenes ensures that 
only one diastereomer is formed.....................................Error! Bookmark not defined. 
Figure 3.1.  An inert-air filtration apparatus.  The reaction mixture is filtered through a glass 
frit from A into flask B. ....................................................Error! Bookmark not defined. 
Figure 3.2.  Schematic diagram of the polymerisation-rig set-up in our laboratory........ Error! 
Bookmark not defined. 
Figure 4.1.  The Tolman cone angle methodology involves the measurement of the half-
 vertex angle for each substituent in an unsymmetrical ligand.Error! Bookmark not 
defined. 
 xi
 Figure 4.2.  Measurement of the cone angle for a methyl substituted cyclopentadienyl 
ligand..............................................................................Error! Bookmark not defined. 
Figure 4.3.  Representation of the ligand angular profile used to create a non-circular cone.
 .......................................................................................Error! Bookmark not defined. 
Figure 4.4.  In the solid angle calculation the atoms are reflected onto a surface and the 
area of that shadow is then integrated. ...........................Error! Bookmark not defined. 
Figure 4.5.  Correction of ring tilt in metallocenes. .................Error! Bookmark not defined. 
Figure 4.6.  Diagram illustrating the co-ordination gap aperture.Error! Bookmark not 
defined. 
Figure 4.7.  Representation of the three conformations adopted by mono-alkyl substituted 
cyclopentadienyl metallocenes in the solid state.............Error! Bookmark not defined. 
Figure 4.8.  Three-dimensional angular ligand profile for the cyclopentadienyl ligand. . Error! 
Bookmark not defined. 
Figure 4.9.  Three-dimensional angular ligand profile for the tertiary-butyl-cyclopentadienyl 
ligand..............................................................................Error! Bookmark not defined. 
Figure 4.10.  Three-dimensional angular ligand profile for the ethylcyclopentadienyl ligand
 .......................................................................................Error! Bookmark not defined. 
Figure 4.11.  Three-dimensional angular ligand profile for the iso-propylcyclopentadienyl 
ligand..............................................................................Error! Bookmark not defined. 
Figure 4.12.  Semi-vertex cone angles for a mono-substituted cyclopentadienyl ligand.Error! 
Bookmark not defined. 
Figure 4.13.  Cone angle ligand profiles ................................Error! Bookmark not defined. 
Figure 4.14.  Tolman cone angle profiles. ..............................Error! Bookmark not defined. 
Figure 4.15.  Solid angle ligand profiles. ................................ Error! Bookmark not defined. 
Figure 4.16.  Numerical solid angle profiles. ..........................Error! Bookmark not defined. 
Figure 4.17.  Ligand Profiles for the cyclopentadienyl ligand. Error! Bookmark not defined. 
Figure 4.18.  Ligand Profiles for the tertiary-butylcyclopentadienyl ligand.Error! Bookmark 
not defined. 
Figure 4.19.  Dependence of Tolman cone angle on M?(CpR) distance.Error! Bookmark 
not defined. 
 xii
 Figure 4.20.  Dependence of the numerical solid angle on M?(CpR) distance.............. Error! 
Bookmark not defined. 
Figure 5.1.  The solid angle is calculated by reflecting the shape of the ligand onto a sphere 
and calculating the size of that shadow. ......................... Error! Bookmark not defined. 
Figure 5.2.  Diagram showing the spaces between the ligand branches in the cone angle.
 .......................................................................................Error! Bookmark not defined. 
Figure 5.3.  Data lines showing the ethene uptake rate for a set of (CpR)2ZrCl2 catalysts.
 .......................................................................................Error! Bookmark not defined. 
Figure 5.4.  Correlation between co-ordination gap aperture and activity.Error! Bookmark 
not defined. 
Figure 6.1.  Numbering scheme used in describing the bis(1-R-indenyl)zirconium dichloride 
metallocenes. .................................................................Error! Bookmark not defined. 
Figure 6.2.  Representation of the three stereoisomers and their symmetry elements.. Error! 
Bookmark not defined. 
Figure 7.1.  The co-ordination gap aperture is measured as the largest possible angle 
between the inner van der Waals surfaces of the ?-substituents on the 5-membered 
ring. ................................................................................Error! Bookmark not defined. 
Figure 7.2.  The ring substituents were orientated in such a way so as to create a minimum 
steric impression when the size of the substituted indenyl ligand was calculated from 
the perspective of the metal............................................Error! Bookmark not defined. 
Figure 7.3.  ORTEP diagram of the two racemic diastereomers of bis-(1-ethyl-
 indenyl)zirconium dichloride (5b) with 40% probability thermal ellipsoids. ............. Error! 
Bookmark not defined. 
Figure 7.4.  Molecular geometry of 5b viewed by looking down the 5-membered rings of the 
indenyl ligands (a) S,S-diastereomer (top) (b) R,R-diastereomer (bottom). ........... Error! 
Bookmark not defined. 
Figure 7.5. (a) ORTEP diagram of bis-(1-phenyl-indenyl)zirconium dichloride (11b) with 40% 
probability thermal ellipsoids (top) (b) 11b viewed looking down the 5-membered rings 
of the indenyl ligands (bottom).  As the second ligand was generated by symmetry, it 
was not numbered. .........................................................Error! Bookmark not defined. 
 xiii
 Figure 7.6.  The ligands in unbridged Group 4 metallocenes can adopt three conformations 
with respect to each other.  These conformers are usually dictated by the size of the 
substituents on the cyclopentadienyl and indenyl ligands.Error! Bookmark not 
defined. 
Figure 7.7.  Waymouth's 2-phenylindenyl metallocene is capable of changing between anti-
 ?rac-like? to a syn-?meso-like? conformations. .................Error! Bookmark not defined. 
Figure 7.8.  In order to prevent steric conflicts as depicted in this diagram, aryl substituents 
are orientated so that they do not lie in the same plane as their parent indenyl moieties.
 .......................................................................................Error! Bookmark not defined. 
Figure 7.9.  Tolman cone angle ligand profiles for the substituted indenyl ligands........ Error! 
Bookmark not defined. 
Figure 7.10.  Analytical solid angle profiles for the substituted indenyl ligands. ............ Error! 
Bookmark not defined. 
Figure 7.11.  Numerical solid angle ligand profiles for the substituted indenyl ligands. . Error! 
Bookmark not defined. 
Figure 7.12.  Comparison of the differences between the three ligand profile calculation 
methodologies, illustrated by considering the tertiary-butyl substituted indenyl ligand.
 .......................................................................................Error! Bookmark not defined. 
Figure 8.2. Ethene uptake rates for the metallocenes studied at low catalyst concentrations.
 .......................................................................................Error! Bookmark not defined. 
Figure 8.3. Ethene uptake rates for the metallocenes studied at high catalyst concentrations.
 .......................................................................................Error! Bookmark not defined. 
Figure 8.4.  Some of the different conformations adopted by 1- and 2-substituted bis-
 (indenyl)zirconium dichloride metallocenes in the solid state.Error! Bookmark not 
defined. 
Figure 8.5.  As the tertiary-butyl group in 7b protrudes below the ligand place, its Tolman 
cone angle is larger than that of 15b. .............................Error! Bookmark not defined. 
Figure 8.6.  Ligand profile plot showing the variation in ligand size as a function of distance 
from the zirconium metal. ...............................................Error! Bookmark not defined. 
 
 xiv
 LIST OF SCHEMES 
 
Scheme 2.1.  The bimetallic species, 5b, was originally thought to be responsible for ethene 
insertion and polymerisation. ..........................................Error! Bookmark not defined. 
Scheme 2.2.  Reaction devised by Eisch and co-workers to disprove that the bimetallic 
system 6a is responsible for ethene insertion.  Instead, a cationic species 6b was 
shown to be the active polymerisation catalyst. ..............Error! Bookmark not defined. 
Scheme 2.3. Reaction scheme, as proposed by Fink, illustrating the insertion of ethene into 
an active polymerisation species (C?P*n) as well as the transition of this species to a 
dormant state (C?Pn) facilitated by an alkylaluminium compound.  Al2
 ?=unknown, 
Al2=(AlEtCl2)2, Pn=polymer chain. ...................................Error! Bookmark not defined. 
Scheme 2.4.  Carbon-carbon bond formation as described in the Cossee-Arlman reaction 
mechanism. 1 .................................................................Error! Bookmark not defined. 
Scheme 2.5.  In the Green-Rooney mechanism a 1,2-hydrogen shift, to form a 
metallocarbene, precedes monomer insertion. ...............Error! Bookmark not defined. 
Scheme 2.6.  In the Brookhart-Green mechanism, the ?-H of the polymer chain bonds 
agostically to the metal during the insertion.  What has not been shown in this scheme 
is how the ?-agostic interaction in the final step reverts to a more favoured ?-agostic 
one. ................................................................................Error! Bookmark not defined. 
Scheme 2.7.  By exploiting the fact that the agostic interaction of H is preferred to that of D, 
Brinztinger was able to prove the existence of agostic interactions.  In the 
hydrodimerisation of (E)- and (Z)-1-[D]-1-hexene, the erythro diastereomers were 
formed in a higher ratio than that of the threo (1.3:1). .....Error! Bookmark not defined. 
Scheme 2.8.  Before ethene inserts into a polymer chain, a rotation around the M-C? bond 
occurs to give an ?-agostic intermediate.  The product, which is a ?-agostic 
intermediate revert to the more stable ?-agostic species.Error! Bookmark not defined. 
Scheme 2.9.  Chain termination by transfer to co-ordinated monomer.Error! Bookmark not 
defined. 
Scheme 2.10.  Termination by chain transfer to the metal. ....Error! Bookmark not defined. 
 xv
 Scheme 2.12.  Chain transfer of the polymer to an aluminium centre.Error! Bookmark not 
defined. 
Scheme 2.13.  By oscillating between between ?rac-like? and ?meso-like? conformations,  
Waymouth?s catalyst can produce isotactic and atactic polymer respectively. ....... Error! 
Bookmark not defined. 
Scheme 2.14.  Donor-acceptor metallocene are capable of equilibrating between bridged 
and unbridged systems...................................................Error! Bookmark not defined. 
Scheme 2.15.  The asymmetric synthesis of ansa-metallocenes can be rendered 
diastereoselective by reacting the stannylated or silylated versions of the ligands with 
the metal chloride. ..........................................................Error! Bookmark not defined. 
Scheme 2.16.  The amine-elimination reaction developed by Jordan and co-workers favours 
the formation of the thermodynamically favoured rac-diastereomer, rac-1............. Error! 
Bookmark not defined. 
Scheme 2.17.  The use of doubly-bridged indenyl ligands allows the synthesis of only one 
diastereomer, thus doing away with tedious separation procedures.Error! Bookmark 
not defined. 
Scheme 2.18.  Resolution of the racemic diastereomers can be achieved by reaction with 
the appropriate lithiated chiral binaphthol. ......................Error! Bookmark not defined. 
Scheme 2.19.  The reaction of (R)-binaphthol with the R- and S-biphenyl bridged 
metallocenes only give the R,R-product indicating that epimerisation of the S-
 diastereomer had occurred. ............................................Error! Bookmark not defined. 
Scheme 5.1.  Reaction scheme, as proposed by Fink, illustrating the insertion of ethene into 
an active polymerisation species (C?P*n) as well as the transition of this species to a 
dormant state (C?Pn) facilitated by an alkylaluminium compound.  Al2
 ? = unknown, Al2 = 
(AlEtCl2)2, Pn = polymer chain......................................... Error! Bookmark not defined. 
Scheme 6.1.  Waymouth's oscillating catalyst in which the bulky indenyl rings slowly rotate 
producing blocks of atactic and isotactic polymer in the same polypropylene chain.
 .......................................................................................Error! Bookmark not defined. 
Scheme 6.2.  Synthesis of an indanone via ring cyclization. ..Error! Bookmark not defined. 
 xvi
 Scheme 6.3.  Indene synthesis via cyclization of a phenyl substituted allylic cation. .... Error! 
Bookmark not defined. 
Scheme 6.4.  Synthetic routes to substituted indene ligands. Error! Bookmark not defined. 
Scheme 6.5.  Rearrangement of indene in the presence of oxygen.Error! Bookmark not 
defined. 
Scheme 6.6.  Formation of the rac- and meso substituted indenyl zirconium complexes.  
Depending on which enantiotopic ligand face attaches to the zirconium metal, one 
meso-diastereomer and two racemic-enantiomers. ........ Error! Bookmark not defined. 
Scheme 6.7.  The rac- and meso- diastereomers could be differentiated form each other by 
converting them to their dimethyl derivatives. .................Error! Bookmark not defined. 
Scheme 8.1.  The bulky phenyl group attached to the indenyl ligands is capable of slowing 
ring rotation down to such an extent, that certain conformations of the metallocene are 
capable of producing elastomeric polypropylene. ........... Error! Bookmark not defined. 
Scheme 8.2.  Conformational rotomeric forms for [2-Ph-Ind]2ZrCl2..Error! Bookmark not 
defined. 
Scheme 8.3.  Possible conformational rotomeric forms for [1-Ph-Ind]2ZrCl2. ................ Error! 
Bookmark not defined. 
Scheme 8.4.  The active polymerisation species C* can be converted to an inactive 
intermediate I2, which can then either be regenerated by MAO to form more active 
catalysts or irreversibly transformed into a second species, I2.Error! Bookmark not 
defined. 
 
 xvii
 LIST OF TABLES 
 
TABLE 2.1.  LIST OF RECENT REVIEW ARTICLES CONCERNING SINGLE SITE CATALYSTS USED FOR 
OLEFIN POLYMERISATIONS. ......................................................... ERROR! BOOKMARK NOT DEFINED. 
TABLE 2.2.  ETHENE POLYMERISATION REACTIONS OF GROUP 4 METALLOCENE CATALYSTS. ERROR! 
BOOKMARK NOT DEFINED. 
TABLE 2.3.  PROPENE POLYMERISATION REACTIONS OF GROUP 4 METALLOCENE / ALUMINOXANE 
CATALYSTS. ................................................................................. ERROR! BOOKMARK NOT DEFINED. 
TABLE 2.4.  ETHENE POLYMERISATION WITH CATIONIC GROUP 4 METALLOCENE CATALYSTS.
 ..................................................................................................... ERROR! BOOKMARK NOT DEFINED. 
TABLE 4.5.  PROPENE POLYMERISATION WITH CATIONIC GROUP 4 METALLOCENE CATALYSTS.
 ..................................................................................................... ERROR! BOOKMARK NOT DEFINED. 
TABLE 4.6.  POLYMERISATION OF OTHER OLEFIN MOLECULES BY GROUP 4 METALLOCENE 
CATALYSTS. ................................................................................. ERROR! BOOKMARK NOT DEFINED. 
TABLE 2.7.  CO-POLYMERISATION REACTIONS INVOLVING GROUP 4 METALLOCENES............ ERROR! 
BOOKMARK NOT DEFINED. 
TABLE 3.1.  SOLVENT PURIFICATION DETAILS............................ ERROR! BOOKMARK NOT DEFINED. 
TABLE 4.5.  VARIATION IN THE TOLMAN CONE ANGLE WITH DISTANCE FROM THE POINT OF 
MEASUREMENT. ........................................................................... ERROR! BOOKMARK NOT DEFINED. 
TABLE 4.6.  VARIATION IN THE SOLID ANGLE WITH DISTANCE FROM THE POINT OF MEASUREMENT
 ..................................................................................................... ERROR! BOOKMARK NOT DEFINED. 
TABLE 4.7.  VARIATION IN THE NUMERICAL SOLID ANGLE WITH DISTANCE FROM THE POINT OF 
MEASUREMENT. ........................................................................... ERROR! BOOKMARK NOT DEFINED. 
TABLE 5.1.  ETHENE POLYMERISATION DATA FOR A SET OF (CPR)2ZRCL2/MAO CATALYSTS.
 ..................................................................................................... ERROR! BOOKMARK NOT DEFINED. 
TABLE 5.2.  COMPARISON OF ETHENE POLYMERISATION RESULTS FROM STUDIES ON THE (C5H5-
 NRN)2ZRCL2/MAO SYSTEM.......................................................... ERROR! BOOKMARK NOT DEFINED. 
TABLE 6.1.  SUMMARY OF 1- AND 2-SUBSTITUTED INDENE SYNTHESES. ....ERROR! BOOKMARK NOT 
DEFINED. 
 xviii
 TABLE 6.2. NMR SPECTRAL DATA FOR THE SUBSTITUTED INDENE LIGANDS......ERROR! BOOKMARK 
NOT DEFINED. 
TABLE 6.3.  NMR SPECTRAL DATA FOR THE BIS-(R-INDENYL)ZIRCONIUM DICHLORIDE 
METALLOCENES. .......................................................................... ERROR! BOOKMARK NOT DEFINED. 
TABLE 6.4.  SELECTED 1H AND 13C NMR DATA FOR THE BIS-(1-R-INDENYL)ZIRCONIUM DICHLORIDE 
METALLOCENES ........................................................................... ERROR! BOOKMARK NOT DEFINED. 
TABLE 6.5.  SELECTED 1H AND 13C NMR DATA FOR THE BIS-(2-R-INDENYL)ZIRCONIUM DICHLORIDE 
METALLOCENES. .......................................................................... ERROR! BOOKMARK NOT DEFINED. 
TABLE 6.6.  MASS SPECTROMETRY FRAGMENTATION DATA FOR THE BIS-(R-INDENYL)ZIRCONIUM 
DICHLORIDE METALLOCENES. ..................................................... ERROR! BOOKMARK NOT DEFINED. 
?ABLE 7.1.  CRYSTAL DATA AND STRUCTURE REFINEMENT FOR 5B............ERROR! BOOKMARK NOT 
DEFINED. 
TABLE 7.2.  CRYSTAL DATA AND STRUCTURE REFINEMENT FOR 11B. ........ERROR! BOOKMARK NOT 
DEFINED. 
TABLE 7.3.  AVERAGE STRUCTURAL PARAMETERS FOR 1- AND 2- SUBSTITUTED BIS-
 (INDENYL)ZIRCONIUM DICHLORIDE METALLOCENES. ................. ERROR! BOOKMARK NOT DEFINED. 
TABLE 7.4.  SELECTED CRYSTALLOGRAPHIC STRUCTURAL DATA FOR 5B AND 11B ................. ERROR! 
BOOKMARK NOT DEFINED. 
TABLE 7.5.  BOND LENGTHS EMPLOYED IN CONSTRUCTING THE (R-IND)?M RING-FRAGMENTS
 ..................................................................................................... ERROR! BOOKMARK NOT DEFINED. 
TABLE 7.6.  COVALENT AND VAN DER WAALS RADII USED IN THE STERIC MEASUREMENTS... ERROR! 
BOOKMARK NOT DEFINED. 
TABLE 7.7.  STERIC MEASUREMENTS FOR A SET OF 1- AND 2-SUBSTITUTED (R-IND)?M FRAGMENTS
 ..................................................................................................... ERROR! BOOKMARK NOT DEFINED. 
TABLE 8.1.  HAMMETT SUBSTITUENT FUNCTIONS FOR A SET OF R-SUBSTITUENTS.................. ERROR! 
BOOKMARK NOT DEFINED. 
TABLE 8.2.  ETHENE POLYMERISATION DATA FOR A SET OF 1- AND 2- SUBSTITUTED (R?
 IND)2ZRCL2/MAO CATALYSTS EMPLOYING LOW METALLOCENE CONCENTRATIONS. ............. ERROR! 
BOOKMARK NOT DEFINED. 
 xix
 TABLE 8.3.  ETHENE POLYMERISATION DATA FOR A SET OF 1- AND 2- SUBSTITUTED (R?
 IND)2ZRCL2/MAO CATALYSTS EMPLOYING HIGH METALLOCENE CONCENTRATIONS. ............ ERROR! 
BOOKMARK NOT DEFINED. 
 
 xx
 ABBREVIATIONS 
 
An : anisidine (4-methoxyaniline), 4-CH3-3,5-tBu2C6H2 
Bz : benzyl, ?CH2(C6H5) 
CCD : Charge-Coupled Device (X-ray crystallography) 
CCp : carbon atom in a cyclopentadienyl ring 
cga : co-ordination gap aperture 
COD : cis, cis-1,5-cyclooctadiene 
Cp : cyclopentadienyl, ?5?C5H5 
cPe : cyclo-pentyl 
Cp* : pentamethylcyclopentadienyl, ?5?C5Me5 
Cpc : the centroid of a cyclopentadienyl or indenyl ligand 
CSD : Cambridge Structural Database 
Cy : cyclohexyl, ?C6H11 
d  : doublet (NMR spectroscopy) 
dd : doublet of doublets (NMR spectroscopy) 
DSC : Differential Scanning Calorimetry 
EAO : ethylaluminoxane 
ebmp : 2,2'-ethylenebis(6-tert-butyl-4-methylphenolato) 
ebthi : 1,2-ethylene-1,1'-bis(?5?tetrahydrohindenyl) 
Et : ethyl, ?CH2CH3 
ETE : Electron Transfer Equilibria 
Flu : fluorenyl, ?5?C13H8 
GC : Gas Chromatography 
HR-MS : High Resolution Mass Spectrometry 
Ind : indenyl, ?5?C9H7 
Indc : the centroid of the 5-membered ring on an indenyl ligand 
IndH4 : tetrahydroindenyl, ?5?C9H11 
iPr : iso-propyl, ?CH(CH3)2 
 xxi
 l.p. : liquid propene 
m : multiplet (NMR spectroscopy) 
Me : methyl, ?CH3 
MAO : methylaluminoxane 
mbmp : 2,2'-methylenebis(6-tert-butyl-4-methylphenolato) 
MW : molecular weight 
MS : Mass Spectrometry 
Naph : Naphthyl, (C10H7) 
n.g : not given. 
NMR : Nuclear Magnetic Resonance 
Pp : pressure at which polymerisation reaction was carried out 
PBB : tris-(2,2',2"-perfluorobiphenyl)borane 
PE : polyethene 
Ph : phenyl 
PNB : tris-(?-perfluoronaphthyl)borane 
PP : polypropene 
cPr : cyclo-propyl 
q : quartet (NMR spectroscopy) 
r.t. : room temperature 
sibmp : 2,2'-sulfinylbis(6-tert-butyl-4-methylphenolato) 
SMART : Small Molecule Analytical Research Tool 
SSC : Single Site Catalyst 
t : triplet (NMR spectroscopy) 
tp : polymerisation time 
Tp : polymerisation temperature 
tBu : tertiary-butyl, -C(CH3)3 
tbmp : 2,2'-thiobis(6-tert-butyl-4-methylphenolato) 
TBS : tertiary-butyldimethylsilyl, ?SiMe2(C(CH3)3) 
TCP : 2-(tetramethylcyclopentadienyl)-4-methylphenolate 
THF : tetrahydrofuran 
 xxii
 TIBA : tri-iso-butylaluminium 
TIPP : 2, 4, 6-tri-(iso-propyl)phenyl 
TIPS : tri-iso-propylsilyl, ?Si(CH(CH3)2)3 
Tm : melting point of polymer 
TMS : trimethylsilyl, ?Si(CH3)3 
TP : hydrotris(pyrazolyl)borate 
TP* : hydro-tris-(3,5-dimethylpyrazolyl)borate 
UV : Ultra-Violet Spectroscopy 
XRD : X-Ray Diffractometry 
XPS : X-Ray Photoelectron Spectroscopy 
Z-N : Ziegler-Natta 
 xxiii
 GLOSSARY 
 
Co-ordination gap aperture, cga The largest possible angle spanned by two planes 
through the metal centre which touch the inner van der 
Waals radii of the ?-substituents at the C5 ligands. 
Cone (or linear) angle, ? The angle between the vectors of right circular cone 
encompassing a group of atoms. 
Numerical solid angle, ?? The non-circular cone angle formed by subtending a 
vector from the point of measurement to the outer van 
der Waals radii of the group of atoms being measured 
and then tracing around these atoms.  The surface of 
the non-circular cone traced out is then integrated. 
Solid angle, ? The surface area of projection onto the inside of a unit 
sphere. 
Cone angle radial profile Plot of the cone angle, ?, as a function of distance from 
the point of perspective. 
Numerical solid angle radial profile Plot of the numerical solid angle, ??, as a function of 
distance from the point of perspective. 
Solid Angle radial profile Plot of the solid angle, ?, as a function of distance 
from the point of perspective. 
 ii