Spectroscopic studies of metal complexes containing π-delocalized sulphur ligands. The resonance-Raman spectra of the antitumor agent [Cu(kts)] and the related cation [Cu(H2kts)]2+

Abstract

The resonance Raman spectra of the antitumor agent [3-ethoxy-2-oxobutyraldehyde bis(thiosemicarbazonato)-(2–)-N¹N¹′SS′]copper(II), [Cu(kts)], and the related cation [Cu(H₂kts)]²⁺ have been measured. In the spectra of both compounds the bands most strongly enhanced are due to skeletal vibrations (CN and CS stretches and ring deformations), while band intensities of metal–ligand vibrations are only slightly modified. Excitation profiles show that the coupling of these vibrations with two π-delocalized sulphur-to-metal charge-transfer transitions is the mechanism responsible for Raman intensity enhancement.