Synthesis of the first acetonylgold(III) complexes by C–H activation of acetone with 2-phenylazophenylgold(III) complexes

Abstract

The complex [[graphic omitted]Ph-2){CH₂C(O)Me}Cl](1) can be obtained by treating [[graphic omitted]Ph-2)Cl₂] with TI(acac)(Hacac = acetylacetone) in acetone at room temperature. At 0 °C or using dichloromethane as solvent, the intermediate [[graphic omitted]Ph-2)(C-acac)Cl](2){C-acac =CH[C(O)Me]₂} can be isolated. Complex (1) can also be obtained by treating [[graphic omitted]Ph-2)Cl₂], in acetone, (i) with KCN (1 : 1), (ii) with [Hg(C₆F₅)₂] and Cl^–(2 : 1 : 2), (iii) with [[graphic omitted]-2}₂](1 : 1), (iv) with AgClO₄(1 : 1), (v) with [Hg(C₆H₄NNPh-2)₂](1 : 1), or (vi) with 1,10-phenanthroline (phen). The probable intermediate in this last reaction [Au(C₆H₄NNPh-2)(phen)Cl₂](3) can be isolated by use of dichloromethane as solvent. Complex (3) is converted into complex (1) when dissolved in acetone. Complex (1) is also obtained from an acetone solution of [Au(C₆H₄NNPh–2)(bipy)Cl]ClO₄(bipy = 2,2′-bipyridyl). This complex reacts in acetone with AgClO₄(1 : 1 ) to give [Au(C₆H₄NNPh-2){CH₂C(O)Me}(bipy)]ClO₄(4). A similar reaction between trans-[Au(C₆H₄NN Ph-2)( PPh₃)₂Cl] ClO₄ and AgClO₄(1 : 1) in acetone gives the dinuclear complex [[graphic omitted]NPh-2)₂( PPh₃)₄][ClO₄]₄(5). A parallel study with [[graphic omitted]Me₂-2)Cl₂] shows a quite different behaviour. It does not react in acetone with [Hg(C₆F₅)₂] and Cl^–(2 : 1 : 2), [[graphic omitted]-2}₂](1 : 1), phen (1 : 1), phen and NaClO₄(1 : 1 : 1), or bipy (1 : 1). However, it does react in acetone with TI(acac)(1 : 1) giving [[graphic omitted]Me₂-2)-(C-acac)Cl](6) or with AgClO₄(1 : 1) giving a solution from which, by addition of phen, the complex [[graphic omitted]Me₂-2)(phen)Cl]ClO₄(7) can be isolated. Complex (7) reacts, in acetone, with AgClO₄(1 : 1) to give [[graphic omitted]Me₂-2)(phen)][ClO₄]₂. A plausible reaction pathway for the C–H activation process is given.