Effect of methyl substituent in pyridine on the spectral and thermal properties of pyridyl adducts of Zn(II) and Cd(II) dithiocarbamate

Four novel pyridine and 2-methyl pyridine adducts of Zn(II) and Cd(II) N-methyl-N-phenyl dithiocarbamates, [Zn(mpdtc)2py], [Zn(mpdtc)2mpy], [Cd(mpdtc)2py2], and [Cd(mpdtc)2mpy] (mpdtc = N-methyl-N-phenyl dithiocarbamates, py = pyridine, mpy = 2-methyl pyridine) have been synthesized. The compounds were characterized by elemental analysis, NMR (1H and 13C) and FTIR spectral techniques. The cadmium compounds were further analyzed by the single crystal X-ray technique. Single-crystal X-ray structural analysis of [Cd(mpdtc)2mpy] showed that cadmium is five-coordinate with four sulphurs from dithiocarbamate and one nitrogen from pyridine, while [Cd(mpdtc)2py2] displayed a six-coordinate geometry with two molecules of nitrogen. The thermal decomposition characteristics (TG/DTG/DSC) of the complexes in the interval 20 to 650 °C were also studied. The spectral and thermal analyses show the influence of the positive inductive effect of the methyl group on the dithiocarbamate. The morphology and composition of the thermal residues were studied using powder XRD and SEM/EDX analyses.