Magnetic and spectroscopic studies on dimeric cobalt(II) complexes of the tetradentate ligand (4,5-Dimethyl-3-pyrazolyl)aldazine

Abstract

Infrared, electronic and electron spin resonance spectral studies together with the molar conductivity and variable temperature magnetic susceptibility data are presented for cobalt(II) complexes of the types: (a) [CoXL]X· 1 2 H 2O,(b)I[Co 2X 3L]X· nH 2O and (c) [Co 2X 4L 2]·H 2O, X = Cl or Br and n 1 2 or 1 and L = (4,5-dimethyl-3-pyrazolyl)aldazine. The formulations are based on elemental analysis and molar conductivity data. Infrared and electronic spectral results show that cobalt(II) complexes are trigonal bipyramidal, tetrahedral and octahedral structures for (a), (b) and (c), respectively. The variable temperature magnetic susceptibility data indicate a weak antiferromagnetic interaction in all complexes. The parameters, J, g, K 2, Dq and B′ are calculated and rationalized in terms of the electronegativity of the coordinated halides and the geometrical shapes. The dimeric nature of class (a) compounds is further substantiated by the complexity of their ESR spectra at 4.8 K.