Carbon-13 N.m.r. and I.r. Studies of copper(I) complexes of the — NHCS group in five- and six-membered heterocyclic rings

Summary Crystalline copper(I) complexes of the general formula LCuCl] and L₂CuCl] were prepared for imidazolidine-2-thiones and 1,3-diazinane-2-thiones by the reduction of copper(II) halides with an excess of the ligands. The¹³C n.m.r. and i.r. spectra of these complexes are consistent with thione sulphur (ligand) donation in all cases. The magnitude of the high-field shift in the¹³C resonance of the thioureide carbon in the complexes as compared with that of the free ligands is interpreted in terms of coordination geometry around the metal atoms. A comparison of the chemical shifts for gold(I), silver(I) and copper(I) revealed a displacement ofca. 6–8 ppm for the mono- and 2–4 ppm for the bis-complexes, respectively.