Abstract The potentially terdentate N, N, S-donor 6-(2 ″-thienyl) 2, 2′-bipyridine (HL), reacts with Na [AuCl 4] to form the complex [Au (HL) Cl 3] in which the ligand acts as a monodentate N-donor. This complex is converted into the cycloaurated compound [Au (L) Cl 2] upon warning. This is the first example of a direct cycloauration reaction of this type, and can be ascribed to non-bonded interactions of the ligand with the metal in [Au (HL) Cl 3].