SPECTRAL AND MAGNETIC STUDIES ON NORMAL COBALT(II) PLANAR AND COBALT(III) OCTAHEDRAL, SPIN-CROSSOVER COBALT(III) OCTAHEDRAL AND PLANAR-TETRAHEDRAL COBALT(II) CARBODITHIOATES

摘要

Five cobalt(II) complexes, a normal complex Co(4-PPipzcdt)(2) (4-PPipzcdt = 4-phenylpiperazine-1-carbodithioate), and four zwitterionic complexes, Co( 4-PPipzcdtH)(2)X(2) and Co(4-MPipzcdtH)(2)X(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)(3)X(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)(3)Cl-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. [References: 21]