Metal–sulphur vibrations. Part I. Far-infrared spectra of some complexes of thiourea and ethylenethiourea (imidazolidine-2-thione)

Abstract

The far-infrared spectra (70–400 cm.^–1) of 36 thiourea and ethylenethiourea (imidazolidine-2-thione) complexes, embracing several different stereochemical types, are assigned and discussed. Metal–sulphur stretching frequencies, v(M–S), lie in the range 298–205 cm.^–1 for the transition-metal complexes, and vary with co-ordination number and electron configuration in the manner now familiar from the behaviour of metal–hylogen stretching frequencies, v(M–X). For Group metals v(M–S) has been found as low as 170 cm.^–1. The similarity between the spectra of thiourea complexes and those of thiocyanates has led to an assignment of the published data for thiocyanates. Some interesting variations in halogen-sensitive vibrations have been encountered.