SYNTHESIS AND SPECTROSCOPIC CHARACTERIZATION OF COBALT(III) COMPLEXESWITH S-BENZYL DITHIOCARBAZATE OF 5-METHYL-3-FORMYL PYRAZOLE (HMPZSB) - X-RAY CRYSTAL-STRUCTURE OF [CO(MPZSB)(2)]CL

The coordination mode of the title ligand, HMPzSB (synthesized for the first time and characterised by elemental analysis, mass, IR and PMR spectral parameters), is reported by solid state isolation and physico chemical identification of cobalt (III) complexes, [Co(MPzSB)(2)]X (X = Cl, ClO4 and BF4). Electronic spectral features of these diamagnetic Co-III species classify them as six-coordinate distorted octahedral o nes. IR spectra (4000-200 cm(-1)) of HMPzSB and its complexes are indi cative of an uninegative tridentate NNS function of the title ligand t hrough the Pyrazolyl (N-2) nitrogen, azomethine nitrogen and thiolato sulphur atom. H-1-NMR data (in d(6)-DMSO at 300 MHz) of the uncomplexe d ligand and its Co-III species are commensurate with the tridenticity (NNS) of the deprotonated form of HMPzSB. X-ray crystallographic stud ies of [Co(MPzSB)(2)]Cl has authenticated that the geometry of the spe cies is distorted octahedral, as envisaged, with the two deprotonated primary ligand systems (MPzSB(-)). The Co-N (azomethine) and Co-N (pyr azolyl) bond lengths are 1.898(4) & 1.954(5) Angstrom and 1.903(4) & 1 .916(5) Angstrom in ligand A & B, respectively where as that of Co-S ( thiolato) is 2.217(2) and 2.255(2) Angstrom in the two ligands. The ex tended planarity of the dithiocarbazate moiety and the pyrazolyl ring of the primary ligand system are maintained because of the ligation ph enomenon to Co-III. (C) 1997 Elsevier Science Ltd.