Synthesis, crystal structure and antibacterial activities of mixed ligand copper(II) and cobalt(II) complexes of a NNS Schiff base

Two new copper(II) complexes of different nuclearities, viz. mononuclear [CuL2(H2O)](ClO4)(2) (1), binuclear [Cu2L2(NCS)(2)(NO3)(2)] (2) and a mononuclear cobalt(II) complex, [CoL2(NCS)(2)] (3), where HL = 2-{[pyridin-2-ylmethylidene]amino}benzenethiol, a tridentate Schiff base derived from 2-aminothiophenol and pyridine-2-al have been prepared. The complexes have been characterized by microanalytical, spectroscopic, single crystal X-ray diffraction and other physicochemical studies. Structural studies reveal that 1 is a mononuclear copper(II) complex with distorted square pyramidal geometry. But, 2 is a thiocyanato-bridged binuclear species in which each copper(II) ion adopts an irregular octahedral geometry containing chelating nitro groups. Complex 3 is comprised of a mononuclear octahedral unit containing two thiocyanato groups in cis positions around the central cobalt(II) ion. The complex units in 1-3 are held together by H-bonding, pi center dot center dot pi or O center dot center dot pi it interactions to develop supramolecular network in their respective solid states. The antibacterial activity of all the complexes along with the constituent Schiff base ligand has been evaluated against some Gram(+) and Gram(-) bacteria. (C) 2014 Elsevier Ltd. All rights reserved.