Spectral and magnetic studies on normal cobalt(II) planar and cobalt(III) octahedral, spin-crossover cobalt(III) octahedral and planar-tetrahedral cobalt(II) carbodithioates

Abstract

Five cobalt(II) complexes, a normal complex Co(4-PPipzcdt) 2 (4-PPipzcdt = 4-phenylpiperazine-1-carbodithioate), and four zwitterionic complexes, Co(4-PPipzcdtH) 2X 2 and Co(4-MPipzcdtH) 2X 2 (X = Cl, Br; 4-PPipzcdtH = 4-phenylpiperazine-1-carbodithioic acid, 4-MPipzcdtH = 4-methylpiperazine-1-carbodithioic acid), have been synthesized. Normal cobalt(III) complexes of the type Co(4-MPipzcdt) 3 and Co 2 {2-MPipz(cdt) 2} 3 (2-MPipz(cdt) 2 = 2-methylpiperazine-1,4-dicarbodithioate) and two zwitterionic cobalt(III) complexes of the type Co(4-MPipzcdtH) 3X 3 (X = Cl, Br) have also been obtained. In addition to the room temperature IR and electronic spectra and magnetic susceptibility studies, all the complexes, except the normal Co(4-MPipzcdt) 3 and Co(4-PPipzcdt) 2 and zwitterionic Co(4-MPipzcdtH) 3Cl 3, have been investigated by variable-temperature magnetic susceptibility measurements. The results of the variable-temperature magnetic susceptibility studies suggest that two cobalt(II) carbodithioates exhibit a square planar-tetrahedral equilibrium, while two cobalt(III) octahedral carbodithioates show a spin-crossover phenomenon.