| Summary: | Controlled pyrolysis of solid Au(SO3F)3 at gradually increasing temperatures up to 145°C produced Au2+ ions as lattice defects. The Au2+ ion was also generated in HSO3F via reduction of Au(SO3F)3(solv) by gold metal. Both types of materials obtained were studied by electron resonance spectroscopy, where spectra indicative of high axial symmetry are obtained. The similar gis0 values indicate that the same species is present in a similar, near square planar environment both in the solid and in the frozen solution. In solution, the Au2+ ion is unstable, and disproportionates to give a diamagnetic, mixed valency compound of the composition AuIituIII(SO3F)4. The orange solid was isolated and studied by vibrational spectroscopy. Dissolution of AulAu111(--3 F)4 in HSO3F produced an ESR active species in a highly unsymmetrical environment, postulated to be[Au(SO3F)4]2-, on account of partly resolved hyperfine splitting to four fluorines. These results have allowed the identification of Au2+ (d9) for the first time.
Reductive carbonylation of Au(SO3F)3 in HSO3F, followed by solvolysis of the product, Au(CO)S03F, in SbF5 in the presence of CO produced [Au(C0)2][Sb2F11], the first example of a linear binary carbonyl cation in a thermally stable isolable compound. The white solid was characterized by vibrational spectroscopy and NMR (19F, 13C)studies. [Au(C0)2][Sb2F11] has a very high average C-0 stretching frequency of
2235.5 cm-1, suggesting that CO is behaving primarily as a a donor, and ir-backbonding is greatly reduced. The Au-C bond is consequently weak, and reaction of a donor solvent such as acetonitrile with [Au(C0)2][Sb2F1i] displaced CO. Slow solvent evaporation gave crystals of [Au(NCCH3)2}[SbF6], which were suitable for a single crystal X-ray diffraction study. [Au(NCCH3)2][SbF6] has completely linear N-Au-N units, and the anion is octahedral. Reductive carbonylation of Pt(SO3F)4 in HSO3F produced [Pt(C0)4][Pt(SO3F)6], which could be further reduced to cis-Pt(C0)2(SO3F)2 with CO by heating. Solvolysis of cis-Pt(C0)2(SO3F)2 in SbF5 in the presence of CO yielded [Pt(C0)4][Sb2F1112.[Pt(C0)4][Pt(S03F)6] and [Pt(C0)4][Sb2F11]2 contain the hitherto unknown square planar[Pt(C0)4]2+ cation. The platinum carbonyl complexes were studied by vibrational spectroscopy, and were found to have very high C-0 stretching frequencies. The averageC-0 stretching frequency for [Pt(CO)4][Sb2F11]2 is 2261 cm-1, and is the highest value so far reported. It was concluded that 7r-backbonding was essentially absent in all the carbonyl complexes obtained here. === Science, Faculty of === Chemistry, Department of === Graduate
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