Spectral, thermal stability and antibacterial studies of copper, nickel and cobalt complexes of N-methyl-N-phenyl dithiocarbamate

Copper(II), cobalt(II) and nickel(II) bis(N-methyl-N-phenyl dithiocarbamate) complexes having the general formula [M{S2CN(MePh)}2] (where M = Cu, Co and Ni) have been prepared and characterized by spectral and thermal analysis. The IR spectra suggest that coordination of dithiocarbamate (DTC) occurred through the two sulfur atoms in a symmetrical bidentate fashion. The electronic spectra, conductance measurement and magnetic moment analysis support the proposed geometry for the electronically dilute complexes. The results of the thermal analysis showed that after dehydration, a one-step decomposition pattern leading to the formation of respective metal sulfide as the end-product occurred. The results are consistent with the proposed composition of the complexes. The in vitro antibacterial activity of the complexes was investigated against strains of gram-negative Escherichia coli, Klebsiella oxytoea and Pseudomonas aureginosa, and gram-positive Bacillus cereus, Staphylococcus aureus and Protues mirabilis. The antibacterial activity of the complexes compared favorably with that of streptomycin and augmentine against S. aureus and B. cereus. The cobalt complex had the best antibacterial activity against the test compounds with inhibitory zone range of 11–14.5 mm.