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    The preparation of new multimetallic materials

    and the functionalisation of nanoparticles with

    transition metal units

    Saira Naeem

    Imperial College London, Department of Chemistry, South Kensington.

    A thesis submitted for the degree of Doctor of Philosophy and the Diploma of Imperial

    College London

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    Statement of Copyright

    The copyright of this thesis rests with the author. No quotation from it should be published without

    the written consent of the author and the information derived from it should be acknowledged.

    Declaration

    I declare that the work described in this thesis was carried out in accordance with the regulations of

    Imperial College London. The work is my own except where indicated in the text and no part of the

    thesis was submitted previously for a degree at this, or any other university.

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    Abstract

    A range of functionalised dithiocarbamates have been prepared and shown to successfully

    coordinate to a series of transition metal complexes which can then be used as a starting point for

    further chemistry. The potential to change the physical properties of these dithiocarbamate (DTC)

    complexes as a whole has been exploited through protonation of amine-terminated compounds. As

    well as rendering the complexes moderately soluble in water, the protonated terminal amine groups on

    the pendant arms can serve as protecting groups for acid-sensitive co-ligands from cleavage or

    unwanted reaction during transformations in the presence of acids.

    An array of diallyl- and methylallyl-terminated DTC complexes have also been formed. The

    successful ring-closing metathesis of the diallyl units again demonstrates that the additional centre of

    reactivity on the pendent arms of the DTC ligand can be utilised, allowing further transformations to

    be carried out without affecting the rest of the complex. Furthermore, the methodology has been

    extended to nanoparticles where diallyl DTC units have been shown to stabilise the surface of gold

    nanoparticles.

    The study was also expanded to include dithiocarboxylate ligands. Few dithiocarboxylate

    complexes are known in literature, thus a comparison with the analogous dithiocarbamate species is

    provided in this report. The first examples of gold(I) complexes of this class of ligand (derived from

    N-heterocyclic carbenes) have been prepared. The synthesis and characterisation of ruthenium-alkenyl

    complexes bearing this ligand have also been presented and evidence of a remarkable rearrangement

    caused by their steric effect has been demonstrated. In addition, it has been shown that imidazolium-

    2-dithiocarboxylate betaines can be used to form monolayers on the surface of gold nanoparticles.

    The synthesis and characterisation of the first ruthenium vinyl complexes bearing the related

    dialkyldithiophosphate ligand, [S2P(OR)2] - are reported here. The resulting compounds demonstrate

    reactivity which differs significantly from that displayed by the analogous dithiocarbamate and

    xanthate compounds.

    Following on from the successful investigations of 1,1-dithio ligands, the scope of these

    explorations was broadened to explore non-sulphur based linkers. These were employed to prepare

    multimetallic compounds through the inherent affinity of certain donor combinations for particular

    metals. Isonicotinic acid was employed to link different metal units to generate heteronuclear bi- and

    trimetallic systems based on careful consideration of their donor properties towards various transition

    metals (Ru, Rh, Pd, Pt, Ag and Au). In most cases, the first metal was shown to preferentially bind to

    the carboxylate moiety, and then the nitrogen of the pyridine ring was used in attempts to coordinate

    further metals. The synthesis of pentametallic complexes using the isonicotinic ligand (based on a

    rhodium core) is also presented, including the successful coordination of ruthenium metal units to the

    carboxylate moiety. The design was extended to explore the palladated tetraphenylporphyrin, [(Pd-

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    TPP)(p-CO2H)4], which illustrated that not only can these metallo-porphyrins be used as a scaffold for

    the addition of peripheral metal units, but also that further functional group transformations can be

    carried out on the terminal units.

    Lastly, having explored the utility of these nitrogen-oxygen mixed-donor ligands in the

    formation of multimetallic compounds, this approach was extended to the surface functionalisation of

    silver nanoparticles. The nitrogen donor groups of these ligands were shown to readily bind to the

    surface of silver colloids, allowing the straightforward attachment of metal units to the surface of

    these materials.

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    Acknowledgements

    First and above all, I thank Almighty God. It is only by His grace and bounty I am able to complete

    this thesis: He gives you of all that you ask Him; and if you reckon the bounties of God, you can never

    count them… (Quran: 14:34).

    I owe sincere and earnest thanks to my supervisor, Dr. James Wilton-Ely, who gave me the

    opportunity to carry out this PhD. Throughout my time of research and writing of this thesis, if it was

    not for his guidance, encouragement and support, I would never have been able to reach the finishing

    line! Words can not express my gratitude.

    I would like to thank the JWE group, both past and present, for providing such enjoyable and

    memorable times in the lab. In particular I would like to thank Ellie Ogilvie, Payel Patel and Angela

    Ribes for their help with the work on dithiocarbamate, dialkyldithiophosphate and mixed-donor ligand

    chemistry, respectively. I have been very fortunate to have worked with such enthusiastic and

    hardworking people who made all those publications possible!

    I wish to express my sincere thanks to the following people, whose input in this research have made it

    possible to produce this thesis:

    Dr. Graeme Hogarth (University College London): collaboration on dithiocarbamate chemistry.

    Prof. Lionel Delaude (University of Liège): collaboration on dithiocarboxylate chemistry.

    Dr. Steve Firth (University College London): TEM images.

    Dr. Mahmoud Ardakani, (Imperial Collge): TEM/EDX.

    Dr. Andrew White (Imperial College): Crystallography.

    Dr. Peter Haycock and Dr. Dick Shepherd (Imperial College): NMR spectroscopy.

    Prof. Andrea Sella (University College London): assistance with molecular mass determinations.

    Dr. Katherine Holt and Muhammed Haque (University College London): CV experiments.

    I thank EPSRC for funding this research project and gratefully acknowledge the support and facilities

    provided by the Department of Chemistry, Imperial College London.

    Thanks to all my friends who have been steadfast in their support: Noor Din, Niraku Ahmad, Helna

    Patel, Fatma Dogan, Sara Ferdousi, Hanan Kamel and Rasha Osman - listening patiently when I

    spoke about my research, trying their best to sound interested!

    (In the Name of God, The Most Beneficent, The Most Merciful)

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    Finally, I wish to extend my warmest thanks to my family, especially to my parents for their continual

    support, understanding and words of encouragement throughout my PhD and for their invaluable

    prayers.

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    Publications

     The functionalisation of ruthenium(II) and osmium(II) alkenyl complexes with amine- and

    alkoxy-terminated dithiocarbamates.

    S. Naeem, E. Ogilvie, A. J. P. White, G. Hogarth and J. D. E. T. Wilton-Ely, Dalton Trans., 2010,

    39, 4080-4089.

     Multifunctional dithiocarbamates: Synthesis and ring-closing metathesis of

    diallyldithiocarbamate complexes.

    S. Naeem, A. J. P. White, G. Hogarth and J. D. E. T. Wilton-Ely, Organometallics, 2010, 29,

    2547-2556.

     Non-innocent behaviour of dithiocarboxylate ligands based on N-heterocyclic

    carbenes.

    S. Naeem, A. L. Thompson, L. Delaude and J. D. E. T. Wilton-Ely, Chem. Eur. J., 2010, 16,

    10971-10974.

     The use of imidazolium-2-dithiocarboxylates in the formation of gold(I) complexes and gold

    nanoparticles.

    S. Naeem, L. Delaude, A. J. P. White and J. D. E. T. Wilton-Ely, Inorg. Chem., 2010, 49, 1784-

    1793.

     Dithiocarboxylate complexes of ruthenium(II) and osmium(II).

    S. Naeem, A. L. Thompson, A. J. P. White, L. Delaude and J. D. E. T. Wilton-Ely, Dalton Trans.,

    2011, 40, 3737-3747.

     Synthesis and reactivity of dialkyldithiophosphate complexes of ruthenium(II).

    P. Patel, S. Naeem, A. J. P. White and J. D. E. T. Wilton-Ely, RSC Adv., 2012, 2, 999-1008.

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    Table of Contents

    1. Chapter 1: Introduction................................................................................................................... 11

    1.1. Multimetallic complexes based on 1,1-dithio ligands........................................................ 12

    1.1.1. Dithiocarbamates.................

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