studies in Early Transition Metal Organometallic Chemistry

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  • Durham E-Theses

    Studies in early transition metal organometallic

    chemistry

    Kingsley, Andrew James

    How to cite:

    Kingsley, Andrew James (1998) Studies in early transition metal organometallic chemistry, Durham theses,Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/4846/

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  • studies in Early Transition Metal

    Organometallic Chemistry

    A thesis submitted in part fulfilment of the degree of Doctor of Philosophy

    Andrew James Kingsley

    Grey College, University of Durham

    February 1998

    The copyright of this thesis rests with the author. No quotation from it should be published without the written consent of the author and information derived from it should be acknowledged.

    2 Alio M

  • Statement of Copyright

    The copyright of this thesis rests with the author. No quotation from it should be published

    without his prior consent and information derived from it should be acknowledged.

    Declaration

    The work described in this thesis was carried out at the University of Durham, Department

    of Chemistry, between October 1994 and September 1997.

    Al l the work is my own unless stated otherwise, and it has not been submitted

    previously for a degree at this or any other university.

  • Publications

    1) Titanium and Zirconium Neopentyl Chloro Complexes, MNpxCU-x (x = 1-4); A.K.

    Hughes and A.J. Kingsley, J. Organomet. Chem., 1997, 539, 109.

    2) Novel Synthesis of Linked Cyclopentadienyl-Amide Complexes; A.K. Hughes and A.J.

    Kingsley, J. Chem. Soc, Dalton Trans., 1997, 4139.

    3) Unexpected Co-Crystallisation of Monomeric and Dimeric Molybdenum Bis Imido

    Complexes; A. Bastanov, J.A.K. Howard, A.K. Hughes, A.J. Kingsley, J.M. Rawson

    and D.F. Wass, Polyhedron, submitted 1997.

  • Acknowledgements

    First and foremost, I would like to thank my supervisor Dr. Andrew Hughes for his

    continued support and encouragement throughout the last three years, without which this

    thesis would not have been possible.

    I 'd like to thank all the occupants of lab 108, who have made the last three years that much

    more enjoyable; Brian Bridgewater, Patrick Gemmell, Andrew Johnson, Sarah Marsh,

    Mark Roden and Melanie Thompson. A l l the inorganic groups deserve a special thankyou

    for making it such a hip and happening section.

    On the technical side, thanks must also go to Gordon Haswell and Ray Hart for their

    glassblowing, Julia Say and Alan Kenwright for their NMR services, Mike Jones and Lara

    Turner for mass spectroscopic analysis, Jaraka Dostal for elemental analysis, Brian Hall for

    standardising many a bottle of "BuLi, and Judith Howard, Angus Mackinnon, Christian

    Lehmann, Janet Moloney and Roy Copley for X-ray crystallography.

    1 would like to give special thanks to Andrew Johnson for his enthusiasm and gathering of

    odds and ends for this thesis. Finally, I thank my Mum, Dad and Michael for continuous

    support throughout.

    ni

  • Abstract

    The work in this thesis is separated into two sections:

    Chapters 1 to 6 are concerned with the synthesis and characterisation of amide

    fimctionalised cyclopentadienyl complexes of Group 4, 5, 6 and 8 transition metals.

    Chapters 7 to 9 involve a study into complexes containing potential a-agostic interactions.

    Chapter 1 provides an infroduction to functionalised cyclopentadienyl complexes

    and also to the ligand C5H5(CH2)3N(H)Me.

    Chapter 2 describes the synthesis of the Group 6 complexes of tungsten and

    molybdenum, M[Ti^:ri'-C5H4(CH2)3NMe](NR)2 by different routes, their chemistry, and

    subsequent reactions.

    Chapter 3 covers the preparation of the Group 4 complexes of zirconium and

    titanium, M[ri*:r|'-C5H4(CH2)3NMe](C5H5)Cl, their subsequent reactions, and potential as

    olefin polymerisation catalysts.

    Chapter 4 contains the synthesis of the Group 5 complexes of niobium and

    tantalum, M[ri*:Ti'-C5H4(CH2)3NMe](N'Bu)(NH'Bu).

    Chapter 5 deals with the preparation of the Group 5 and 6 vanadium and

    chromium chloride complexes M[r|^:ri'-C5H4(CH2)3NMe]Cl, their reactions, and potential

    as olefin polymerisation catalysts.

    Chapter 6 descibes the preparation of some iron complexes. The synthesis of the

    ferrocene, Fe[r|^-C5H4(CH2)3N(H)Me]2, and the bridged carbonyl complex, {Fe[r|^:ri'-

    C5H4(CH2)3N(H)Me](CO)(^-CO)}2, are described.

    Chapter 7 provides an infroduction to a-agostic interactions, the use of the

    Isotopic Perturbation of Resonance (IPR) technique as a means of characterisation, and the

    preparation of deuterated starting materials to perform such investigations.

    Chapter 8 investigates the complexes MeTiC^L (L = dme, tmeda, diphos),

    W(N'Bu)2Me2, and Mo(N-2,6-'Pr2C6H3)2Me2 for a-agostic interactions, using the IPR

    technique

    Chapter 9 describes the synthesis of and investigation for a-agostic bonds in

    zirconium and titanium neopentyl chloro complexes MNpxCU-x (x = 1 - 4).

    The Appendices outline the preparative and analytical methods used, and X-ray

    crystallographic data.

    iv

  • Abbreviations

    "Bu "Butyl group, C4H9

    'Bu ^Butyl group, C(CH3)3

    *Pr Isopropyl group, CH(CH3)2

    Ph Phenyl group, CeHs

    Me Methyl group, CH3

    Np Neopentyl group, CH2C(CH3)3

    Ts Tosylate group, 3-CH3C6H4SO2

    Ar" 2,6-[(CH3)2CH]2C6H3

    Ar^ 3-CF3C6H4

    dmpe Dimethylphosphinoethane, CH3PCH2CH2PCH3

    dme 1,2-dimethoxyethane, CH3OCH2CH2OCH3

    tmeda N,N,N',N'-tetramethylethylenediamine, (CH3)2NCH2CH2N(CH3)2

    diphos 1,2-bis(diphenylphosphino)ethane, Ph2PCH2CH2PPh2

    T H F Tetrahydrofiiran, C4H8O

    TMS Trimethylsilyl, (CH3)3Si

    DMSO Dimethyl Sulphoxide, (CH3)2SO

    HMPA Hexamethylphosphoramide

    L General two electron ligand

    X General one electron ligand

    Z Carbon or silicon bridge

    R Any hydrocarbon group

    CpH Cyclopentadiene, CeHs

    CpNMe C5H4(CH2)3NMe

    F A L Tris Fluoro Alkyl Aluminoxane

    MAO Methyl Aluminoxane, [AlOMeJn

    IR Infra-Red

    NMR Nuclear Magnetic Resonance

    C O S Y correlation Spectroscopy

    H E T C O R HETeronuclear CORrelation

    N O E Nuclear Overhauser Effect

  • MO Molecular Orbital

    HOMO Highest Occupied Molecular Orbital

    IPR Isotopic Perturbation of Resonance

    *

    Abbreviations for IR and NMR spectra

    s singlet

    d doublet

    t triplet

    q quartet

    quin quintet

    sept septet

    m multiplet

    br broad

    A 5 A [ 6 ( C H 3 ) - 5 ( C H 2 D ) ]

    S solvent

    impurity

    V I

  • Contents

    Chapter 1 - Introduction to Amide Functionalised Cyclopentadienyl Complexes

    1.1 Metal-Cyclopentadienyl Chemistry 1

    1.1.1 Metallocenes 1

    1.1.2 Bis cyclopentadienyl complexes (araa-metallocenes) 2

    1.1.3 Functionalised cyclopentadienyl complexes 3

    1.2 LX Functionalised Cyclopentadienyl Systems 6

    1.2.1 Complexes with amide functionalised cyclopentadienyl ligands 6

    1.2.2 Alkyl and hydrido complexes 10

    1.2.3 Structure 12

    1.2.4 Complexes with alkoxo fimctionalised cyclopentadienyl ligands 14

    1.2.5 Complexes with polydentate amide functionalised 16

    cyclopentadienyl ligands

    1.3 Application of Amide Functionalised Cyclopentadienyl 17

    Complexes in Catalysis

    1.3.1 Ziegler-Natta catalysis 17

    1.3.2 Polymerisation of ethylene and a-olefms 17

    1.3.3 Hydrogenation and hydroboration 20

    1.4 Preparation of Amide Functionalised Cyclopentadienyl Complexes 22

    1.4.1 Synthesis of amine functionalised cyclopentadienyl ligands 23

    1.4.2 Synthesis of C5H5(CH2)3N(H)Me, 1.1 23

    1.4.3 Synthesis of lithium salts: a) [C5H4(CH2)3N(H)Me]Li. 1.2 27

    b) [C5H4(CH2)3NMe]Li2,1.3 29

    1.4.4 Synthesis of [C5H4(CH2)3NMe](SiMe3)2,1.4 29

    1.4.5 Previous work with C5H5(CH2)3N(H)Me, 1.1 30

    1.5 Aims 33

    1.6 Experimental 34

    1.6.1 Preparation of C5H5(CH2)3N(H)Me, 1.1 34

    1.6.2 Preparation of [C5H4(CH2)3N(H)Me]Li, 1.2 37

    1.6.3 Preparation of [C5H4(CH2)3NMe]Li2,1.3 37

    1.6.4 Preparation of [C5H4(CH2)3NMe](SiMe3)2,1.4 37

    1.7 References 38

    vii

  • Chapter 2 - Group 6 - Tungsten and Molybdenum Amide Functionalised

    Cyclopentadienyl Complexes.

    2.1 Infroduction 42

    2.1.1 Bis-cyclopentadienyl (a5a) complexes 42

    2.1.2 Nifrogen fiinctionalised cyclopentadienyl complexes 43

    2.1.3 Aims 45

    2.2 Synthesis of Amide Functionalised Cyclopentadienyl Complexes 46

    2.2.1 Reaction between W(N*