Acylseleno- and acylthioureato complexes of gold(<scp>i</scp>) N-heterocyclic carbenes

A series of gold(I) N-heterocyclic carbene complexes containing monoanionic acylchalcogenourea (chalcogen = S, Se) ligands was prepared and characterised by various spectroscopic methods and X-ray diffraction. The compounds were conveniently accessible in good yields through a one-pot reaction involving [AuCl(tht)] (tht = tetrahydrothiophene), the imidazolium salt and the acylchalcogenourea in the presence of excess base. The X-ray diffraction experiments showed that in these complexes, the normally chelating ligands adopt the rare κS/Se-coordination mode in which only the chalcogen is bound to gold.