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New microwave methods were developed for the synthesis of cationic and neutral gold(III) complexes. Six examples of [AuCl2(N–N)][PF6], containing 2,2′-bipyridine-type ligands, and three examples of AuCl2(C–N), containing cyclometallated 2-phenylpyridine-type ligands, were successfully prepared. Two of the complexes, [AuCl2(5,5′-dimethyl-2,2′-bipyridine)][PF6] and [AuCl2(4,4′,5,5′-tetramethyl-2,2′-bipyridine)][PF6], have not been previously reported. Generally, the microwave-heated reactions gave analytically pure products within minutes – a substantial improvement over conventional procedures. In conjunction, the thermal stabilities of some of the complexes were studied by thermogravimetric analysis. The transformation of AuCl3(2-(p-tolyl)pyridine) into its cyclometallated analog AuCl2(tpy), marked by the loss of a mass corresponding to HCl, was observed.

A series of new L2PtMe2 and L2PtPh2 complexes have been prepared, where L2 = chelating diimine or NHC iminocarbene ligands with similar substituent patterns. These have been investigated by 1H- and 13C-NMR spectroscopy and single-crystal X-ray structure determinations to assess differences between the two ligand systems. All the three approaches underscore the strong trans influence of the N-heterocyclic carbene moiety relative to the imine group. This is supported by trends in J(195Pt–H) and J(195Pt–C) coupling constants in the hydrocarbyl NMR resonances as well as in differences in Pt–ligand bond distances trans to the imine and carbene moieties. This is paralleled by a clear trans effect of the carbene ligand in protonolysis; treatment of the Pt(II) dimethyl or diphenyl iminocarbene complexes with acid causes the elimination of methane and benzene, respectively, with selective loss of the methyl or phenyl groups from the trans position relative to the carbene part of the chelating ligand.

Design of a selective homogeneous methane functionalizing catalyst based on [(ArN=CRCR=NAr)Pt(Me)(L)]+ requires knowledge of its stability in various reaction media, particularly water. Reaction of (diimine)PtMe2 (1) (diimine = ArN=CRCR=NAr, Ar = 2, 6-Me2C6H3, R = Me) with HOTf (OTf = OSO2CF3) gives the methane activating compound (diimine)Pt(Me)OTf (3). When varying amounts of H2O are added during the synthesis of 3, competing degradation pathways lead to two different characterizable products. With only trace amounts of water, two dimeric species, [(diimine)Pt(μ-Cl)(μ-OH)Pt(diimine)](OTf)2 (6) and [(diimine)Pt(μ-OH)2Pt(diimine)](OTf)2 (7), are isolated, in addition to an uncharacterized dark brown precipitate. When an excess of H2O is added, the aquo species [(diimine)Pt(Me)(H2O)][OTf] (5) is first observed, which then reacts further to give a dark brown precipitate and 7. The structures of 1, 6, and 7 are presented. Both 6 and 7 exhibit unusual conformations for their respective classes. Compound 6 has...