(β-Diketiminato)dimethylgold(III): Synthesis, Structure, and Reactivity

The reaction between [Me2AuCl]2 and the lithium salt of a β-diketimine, [HC{C(Me)N(C6H3-2,6-Me2)}2Li], yields the neutral Au(III) compound [HC{C(Me)N(C6H3-2,6-Me2)}2AuMe2] (1). Compound 1 reacts with 1 equiv of triflic acid (HOTf) at −78 °C to provide the cationic Au(III) compound [H2C{C(Me)N(C6H3-2,6-Me2)}2AuMe2][OTf] (2). Treatment of 1 with 2 equiv of HOTf results in the displacement of Me2AuOTf and formation of the β-diketiminato triflate salt [HC{C(Me)NH(C6H3-2,6-Me2)}2][OTf] (3). Compound 1 reacts with I2 to yield the cation [HC(I){C(Me)N(C6H3-2,6-Me2)}2AuMe2]+, which is isolated as the triflate salt [HC(I){C(Me)N(C6H3-2,6-Me2)}2AuMe2][OTf] (4). The reaction of 1 with (PPh3)AuCl in the presence of AgOTf provides [HC(AuPPh3){C(Me)N(C6H3-2,6-Me2)}2AuMe2][OTf] (5). Molecular structures of 1, 4, and 5 were elucidated by single-crystal X-ray diffraction experiments; that of 4 was additionally confirmed by quantum-chemical calculations. The reactivity experiments indicate that the methine carbon in the β-diketiminato unit of 1 is the exclusive site of electrophilic attack, while the Au−C bonds are not perturbed.