Reactions of dichloro[2-(dimethylaminomethyl)phenyl-C1,N]gold(III), [Au(damp-C1,N)Cl2], with heterocyclic thiols. Evidence for Au–N bond cleavage and protonation of the dimethylamino group

Abstract

Dichloro[2-(dimethylaminomethyl)phenyl-C¹,N]gold(III), [Au(damp-C¹,N)Cl₂], reacts with 2-mercapto-1,3-thiazoline (HSthiaz), 2-mercaptopyridine (HSpy), sodium 1-methylmercaptotetrazolate (NaSmetetraz), 4-methyl-3-mercapto-1,2,4-triazole (HSmetriaz) or 6-mercaptopurine (HSpur) under cleavage of the Au–N bond and protonation of the dimethylamino group. Compounds of general formulae [Au(Hdamp-C¹)Cl(HL)₂]²⁺ (HL = HSthiaz or HSpy), [Au(Hdamp-C¹)Cl(L)] (L = Spur^–) or [Au(Hdamp-C¹)(L)₃] (L = Smetetraz^–) have been isolated and characterized. The reaction with HSmetriaz leads to a rapid reduction of the metal and the formation of the gold(I) complex [Au(HSmetriaz)₂]⁺. The crystal structures of [Au(Hdamp-C¹)Cl(HSthiaz)₂]Cl₂·Me₂CO, [Au(Hdamp-C¹)Cl(HSpy)₂]·H₂O, [Au(Hdamp-C¹)(Smetetraz)₃] and [Au(Hdamp-C¹)Cl(Spur)]Cl have been elucidated showing the gold atoms in distorted square-planar co-ordination environments. Generally, one or more hydrogen atoms of the heterocyclic ligands and/or the NMe₂H⁺ group form hydrogen bonds in the solid-state structures. The reaction of Na[AuCl₄] with Na(Smetetraz) and [NEt₄]Br yields bright red crystals of [NEt₄][Au(Smetetraz)₄], the first structurally characterized gold(III) complex with four monodentate thiolate ligands. The structure of the complex shows well separated [Au(Smetetraz)₄]^– anions with Au–S distances of 2.354(4) Å.