Facile syntheses of four-membered aurathietane dioxide [Au–CHR-SO2-CHR] ring systems, and the first isonitrile insertion reaction into a gold(III)–carbon bond

Cyclometallated gold(III) complexes derived from 2-benzylpyridine, 2-anilinopyridine [AuCl2(C5H4N-X-C6H4)] [X = CH2 (2-bp) or NH (2-anp)] or 2-p-tolylpyridine (tolpy) [AuCl2(C5H4NC6H3CH3)] react with the sulfones RCH2SO2CH2R (R = CN or COPh) in hot methanol with added trimethylamine base to give new aurathietanedioxide complexes containing the Au(CHRSO2CHR) four-membered ring system. The previously reported cyclo-aurated dimethylbenzylamine (MeO-damp) complex [Au{CH(COPh)SO2CH(COPh)}(Me2NCH2C6H3OMe)] was also synthesised by this method, and found to exist as a mixture of major (trans) and minor (cis) isomers with respect to the orientation of the COPh substituents across the four-membered ring. The reaction of one complex with tBuNC in refluxing dichloromethane results in insertion of the isonitrile into the Au–C bond trans to the phenyl ring, followed by proton transfer. An X-ray crystal structure determination on this product was carried out.