A variety of gold(III) adducts having σ-ligated oxygen-donor ligands have been prepared from [Au(bpy)Cl₂][PF₆] 1 (bpy = 2,2′-bipyridine) either by partial or total replacement of the chloride ions. The new species comprise hydroxo, [Au(bpy)(OH)Cl][PF₆] 2 and [Au(bpy)(OH)₂][PF₆] 3, oxo, [Au₂(bpy)₂(μ-O)₂][PF₆]₂4, acetato, [Au(bpy)(O₂CMe)₂][PF₆] 5, and alkoxo complexes, [Au(bpy)(OR)Cl][PF₆] 6, 7 and [Au(bpy)(OR)₂][PF₆] 8–10 (R = Me 6 and 8; Et 7 and 9; Prⁱ10). The dihydroxo and the oxo complexes can be interconverted by refluxing the former in anhydrous THF and the latter in water. The hydroxides 2 and 3 and the acetato complex 5 undergo σ-ligand metathesis in ROH solution (R = Me, Et or Prⁱ) to give the corresponding alkoxides. The crystal structure of 8, the first of a gold(III) methoxo complex, has been determined by X-ray diffraction analysis.

The reactivity of a series of gold(III) adducts [Au(HL)Cl₃] 1a–4a with 6-alkyl-2,2′-bipyridines HL (N₂C₁₀H₇R, R = CH₂Me 1, CHMe₂ 2, CMe₃ 3 and CH₂CMe₃ 4) has been studied. The reactions of 1a–4a with silver(I) ions or MeCO₂Na afford cationic complexes [Au₂(HL)₂(µ-O)₂]²⁺ 1b–4b (as BF₄ or PF₆ salts) having the gold atom bonded to the nitrogen atoms of the bipyridine and to two oxygen atoms. The crystal structure of 4b[PF₆]₂, solved by X-ray diffraction, shows that the cation is a centrosymmetric dimer with two oxo (O^2–) groups bridging two [Au{N₂C₁₀H₇(CH₂CMe₃)-6}] moieties. In the case of 2a, besides the oxo species, mononuclear ionic derivatives [Au(L*)Cl]⁺ 2*c [HL* = N₂C₁₀H₇(CMe₂OH)-6; BF₄, PF₆ or AuCl₄ salts] have been isolated. The latter complexes contain an unexpected Au–O bond. The spectroscopic data and the crystal structure of 2*c[AuCl₄] indicate a tridentate N,N,O behaviour of the ligand which forms a [5,5]-fused ring system.

Replacement of the chloride ligand in the cyclometallated complexes [Au(C,N,N)Cl][PF₆] (C,N,N = N₂C₁₀H₇(CH₂C₆H₄)-6 1, N₂C₁₀H₇(CHMeC₆H₄)-6 2, or N₂C₁₀H₇(CMe₂C₆H₄)-6 3, where N₂C₁₀H₈ = 2,2′-bipy) by C, N, O and S donor anionic ligands Y was accomplished through different routes depending both on the nature of HY or the C,N,N ligand. Stable alkoxo [Au(C,N,N)(OR)][PF₆] (R = Me or Et) and amido [Au(C,N,N)(NHAr)][PF₆] (Ar = C₆H₄NO₂-4) complexes were obtained in fairly good yields. The molecular structure of the thiolato complex [Au{N₂C₁₀H₇(CMe₂C₆H₄)-6}(SPh)][PF₆] has been determined by X-ray crystallography. The diorganogold(III) complex [Au(C,N,N)(C₂Ph)][PF₆] on addition of PPh₃ (1∶2) undergoes reductive elimination to give [Au(PPh₃)₂][PF₆] and an unsymmetric diarylacetylene.