Synthesis, characterization and antimicrobial activity of some nickel, cadmium and mercury complexes of 5-methyl pyrazole-3yl-N-(2′-methylthiophenyl) methyleneimine, (MPzOATA) ligand

Abstract

Herein, we report the syntheses and structures of Ni(II) complexes, [Ni(MPzOATA)2] (Cl) (PF6) (I), [Ni(MPzOATA)2](ClO4)2.CH3CN (II) & [Ni(MPzOATA)2](BF4)2.H2O (III); Cd(II) complex, [Cd(MPzOATA)Cl2]2 (IV) and a Hg(II) complex, [Hg(MPzOATA)Cl2] (V), of a pyrazole based ‘NNS’ donor ligand, 5-methylpyrazole-3yl-N-(2′-methylthiophenyl)methyleneimine, (MPzOATA). The complexes are characterized by elemental analyses, electronic, IR, 1H- NMR (only for IV &V) spectral parameters, conductivity and fluorescence measurements. X-ray crystallographic data of the complexes reveal that the Ni(II) complexes have NiN4S2 octahedral coordination, one of them is a mixed-anion complex having Cl− and PF6− as counter anions; the Cd(II) complex is a chloro bridged binuclear complex with octahedral coordination environment around each metal centre, while the Hg(II) complex is a square pyramidal one. Among the reported complex species, the Ni(II) complexes are non-fluorescent, while the Cd(II) and Hg(II) complexes can be used as potential photoactive materials as indicated from their characteristic emission properties. The reported complexes are screened for their antimicrobial activities against some Gram positive and Gram negative microbial strains, and they are found to be potential antimicrobial agents in broad spectrum against both Gram positive and Gram negative bacteria.