Synthesis, spectroscopic and structural characterization of the mer isomer of ammonium bis(phenylpyruvic acid thiosemicarbazone)-cobalt(III) hemihydrate

Abstract

Phenyl pyruvate thiosemicarbazone (H2PPVATSC) coordinates in its binegative thiolate form to cobalt(III) in the complex isolated from basic medium. An X-ray structure determination of the resulting meridional isomer was found to contain mutually cis sulphur, trans nitrogen, and trans oxygen donor atoms, respectively. The two five-membered rings formed by each ligand are puckered towards each other, resulting in a distortion from regular octahedral geometry about the cobalt atom. The complex was found to exhibit only a metal-based one electron reversible reduction at -0.97 V, while the parent ligand yields a c.v. profile consisting of two irreversible reduction peaks at -0.75 and -1.05V respectively, the latter corresponding to the reduction of the azomethine group.