Synthesis and structural characterization of Ni(II) complexes containing a heterocyclic NO donor ligand

Five novel nickel(II) complexes have been successfully synthesized with a heterocyclic ligand, Opdac, [Ni(Opdac)(2)]Cl-2 (1), [Ni(Opdac)(2)(CH3OH)(2)]Br-2(CH3OH)(2) (2), [Ni(Opdac)(2)]I-2 (3), [Ni(Opdac)(2)NO3]NO3 (4) and [Ni(Opdac)(2)ClO4]ClO4 (5) where Opdac = 4-(1-H-1,3-benzimidazole-2-yl)-1,5-dimethyl-2-phenyl-1-2-dihydro-3-H-pyrazol-3-one. All the complexes were characterized by elemental analysis, molar conductivity, CHN analysis, magnetic susceptibility measurements, spectroscopic studies and TG/DTA methods. In all the complexes, Opdac acts as a bidentate ligand coordinating to Ni(II) ion via the benzimidazole imine nitrogen and the pyrazolone oxygen atoms. The complexes 1 and 3 have a tetrahedral geometry while 2, 4 and 5 have an octahedral geometry around the Ni(II) center. (C) 2011 Elsevier Ltd. All rights reserved.