Infrared absorption spectra of metal complexes of alkylthioureas and some related ligands

The i.r. spectra of metal complexes of thioacetamide, thiourea, ethylenetrithiocarbonate, N-methylacetamide, N-methylthiourea, N,N′-dimethylthiourea and tetramethylthiourea have been examined in the 4000–4250 cm−1 region. The co-ordination is through sulphur in the complexes of thioacetamide, thiourea, ethylenetrithiocarbonate and tetramethylthiourea. N-methylthiourea and N-N′-dimethylthiourea show ambident behaviour wherein the co-ordination is through nitrogen or sulphur. It is difficult to assign structures of complexes on the basis of the frequency shifts particularly when the bands arise from mixed vibrations. Far i.r. spectra would, however, be useful in identifying metal-ligand vibrations.