The general use of i.r. spectral criteria in discussions of the bonding and structure of metal dithiocarbamates

Abstract

Normal coordinate analyses of a series of chromium (III) dithiocarbamates are reported. Variation of the alkyl substituent is shown to produce both kinematic and electronic effects on the thioureide band at ca. 1550 cm −1 and to effect profoundly the degree of mixing of the asymmetric N-alkyl and symmetric C S modes in the 1000 cm −1 region. Vibrational analyses are also reported on model monodentate and unsymmetrical bidentate dithiocarbamate complexes. The Ugo—Bonati distinguishing monodentate and bidentate bonding by the number of observed bands in the 1000 cm −1 region is shown to be valid, provided comparison is made between complexes containing the same alkyl group, but unsymmetrical bidentate bonding is shown to produce similar splitting effects to those of the monodentate case although smaller in magnitude and consequently it is suggested that only if the splitting in the 1000 cm −1 region is greater than 20 cm −1 should monodentate bonding be assumed.