Synthesis and spectral characterization of 1-phenylglyoxal bis{N(4)ethylthiosemicarbazone} and its metal complexes

Nickel(II), copper(II), zinc(II), and cadmium(II) complexes of 1-phenylglyo xal bis{N(4)-ethylthiosemicarbazone} have been synthesized and characterize d spectroscopically. The bis(thiosemicarbazone) and its diamagnetic complex es have been characterized by their melting points, i.r., electronic, mass and H-1 n.m.r. spectra. The four-coordinate copper(II) complex was also stu died by e.s.r. spectroscopy. Upon coordination, the loss of a proton from e ach thiosemicarbazone moiety occurs, and the bis(thiosemicarbazone) coordin ates to nickel(II) and copper(II) as a dianionic, tetradentate N2S2 ligand; but for zinc(II) and cadmium(II), mass spectral results suggest the format ion of binuclear complexes.