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Title: Studies of low oxidation state group 13 halide, hydride and heterocyclic complexes
Author: Kloth, Marc
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2004
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The work presented in this thesis describes the synthesis, structure and stability of a range of halido, hydrido and heterocyclic complexes of the group 13 elements. The underlying theme is the synthesis of low valent group 13 complexes. The work upon this subject is divided into five chapters. Chapter 1 provides a general introduction to the members of group 13 and to low oxidation state group 13 halide chemistry. The history of binary group 13 metal trihydride complexes and the reasons behind their inherent instability are also discussed. Chapter 2 details the use of a stable nucleophilic N-heterocyclic carbene, l,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene. (IPr), and nitrogen donor ligands, namely a bulky diazabutadiene (Ar-DAB), Ar = 2.6-Pr'2C6H3. quinuclidine and formamidinate, in the formation of group 13 trihalide complexes. A series of metal trihalide complexes have been prepared and characterised, e.g. InBr3(L) . L = IPr or Ar-DAB, whose reduction reactions with alkali metals did not yield low valent metal metal bonded group 13 species. In addition, the reactivity of "Gal" towards pyridine based ligands is described: 'Gal* reacts, for example, with 2.2'-bipyridine (bipy) to give salts of composition Ga(bipy)3 I 3, ((bipy)2Ga}2(u-OH)2 : Ga2l6 l 6 or {(bipy)2Ga 2(u-OH)2 I 4. depending upon the reaction conditions. All new compounds have been crystallographically characterised. Chapter 3 introduces the reactivity of diazabutadienes (Ar-DAB or Bul-DAB) towards low oxidation state group 13 iodides which afforded, for example, the paramagnetic compounds. {IGa(But-DAB)}2, I2Al(Ar-DAB) and {CHn(Ar-DAB)}2 which have been characterised by X-ray crystallography and EPR spectroscopy. In addition, the synthesis of the second example of an anionic gallium(I) N-heterocyclic carbene analogue. {(TMEDA)KGa(Ar-DAB)}2, is described. This complex displays a Ga Ga interaction in the solid state which is unprecedented for this complex type. Chapter 4 lists reactivity studies of a new gallium(I) carbene analogue, {(TMEDA)KGa(Ar-DAB)} 2. towards main group halide complexes. These studies led to some decomposition products which are paramagnetic and have been studied both crystallographically and by EPR spectroscopy. The reactivity of the gallium carbene analogue towards sources of oxygen has been investigated and the complex, ((u-0)Ga(Ar-DAB)2}2 2 from the reaction with N2O. has been isolated and structurally characterised. In addition, an unprecedented 7t-cyclopentadienyl bridged digallane complex, {Ga(Ar-DAB)2h{u-CpK(TMEDA)2}. incorporating the first structurally characterized -interaction with a Ga(II) center, results from the oxidative coupling of an anionic gallium(I) heterocycle with cyclopentadienyl thallium(I). Chapter 5 introduces the known hydride chemistry of indium and describes the synthesis of a number of novel group 13 hydride complexes. These include the preparation and characterisation of the first examples of amido indium hydride complexes, one of which has unprecedented thermal stability. In addition, these studies led to the first covalently bonded metal complexes derived from an anionic gallium carbene analogue, one of which, InH2{Ga(Ar-DAB)}2 Li(TMEDA)2, contains the first example of a structurally authenticated In Ga bond. This chapter also includes the preparation and characterisation of a subvalent pentaindium cluster compound.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available