New developments in the coordination chemistry of Gold(I), Gold(II) and Gold(III) with C-, N- , P-and S-donor ligands

Coetzee, Jacorien (2007-03)

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2007.


A comprehensive, comparative structural study of gold(I), gold(II) and gold(III) compounds with the general formula [Aux(C6F5)y(tht)z] (tht = tetrahydrothiophene) was performed. The series of compounds included the unprecedented dinucleur gold(II) compound, tetrakis(pentafluorophenyl)bis(tetrahydrothiophene)digold(II), which could be prepared in a rational manner. This very unique compound represents the first example of an unbridged dinucleur gold(II) compound in which the gold(II) centres are not stabilised by chelating ligands. Formation of this compound was postulated to have taken place by radical pentafluorophenyl (pfp) ligand migration along with AuII–AuII bond formation. It may therefore be regarded as a rare example of labile behaviour by a generally inert pfp ligand. In addition to this compound, the crystal and molecular structures of the wellknown gold(I) and gold(III) precursor compounds, (pentafluorophenyl)(tetrahydrothiophene) gold(I) and tris(pentafluorophenyl)(tetrahydrothiophene)gold(III) were carried out and are described for the first time. The latter underwent a unique mononuclear ligand rearrangement (metathesis or disproportionation) reaction in solution to yield the novel rearrangement product, bis(pentafluorophenyl)bis(tetrahydrothiophene)gold(III)tetrakis- (pentafluorophenyl)gold(III). In all the complexes, the Au–C and Au–S bond lengths displayed a variation which appears to be dependent on the oxidation state of the central gold atom. Both of these bond types were found to descrease in the order Au(II) > Au(III) > Au(I)...

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