Mixed-ligand complexes of gold(I) and silver(I) with heterocyclic thiones

Novel mixed-ligand complexes of Ag¹ and Au¹ containing triphenylphosphine (TPP) and heterocyclic thiones, of general formula [TPP-M-L]Cl and [(TPP)₂-M-L]Cl, where L=imidazolidine-2-thione (Imt), 1,3-diazinine-2-thione (Diaz) or N-isopropylimidazolidine-2-thione (iPrImt) have been prepared. The spectroscopic data are consistent with S-donation in all complexes. The magnitude of high-field shift in carbon-13 n.m.r. of the thioureide carbon on complexation is interpreted in terms of coordination geometry around the metal atoms. The mixed-ligand complexes are structurally similar to some of the commonly used antiarthritic Au¹ drugs and are thus potentially useful in chemotherapy.