Synthesis, Spectroscopic and Electrochemical Study of Mn(II) Complexes of N-methylbenzyl, Phenylpiperazyl- and Morpholinyl- dithiocarbamate

Abstract

Mn(II) complexes of N-methylbenzyl-(L1), phenylpiperazyl-(L2) and morpholinyl-(L3) dithiocarbamates formulated as [Mn(L1)2] 1, [Mn(L2)2] 2 and [Mn(L3)2] 3 were synthesized and characterized by elemental analysis and spectroscopic techniques. The FTIR spectra confirmed the dithiocarbamate molecules coordinated the Mn(II) ion as bidentate chelating ligands by the single ν(C-S) bands observed in the range 940-994 cm-1 and the ν(C-N) stretching vibrations observed in the region1462-1483 cm-1. The EPR studies of the compounds showed broad signals for complexes 1 and 3 with g values of 2.223 and 2.164 at 25 °C and 2.005 and 2.013 at-196 °C respectively and hyperfine coupling constant (A) of 98.65 and 84.64 G respectively. Complex 2 showed six lines hyperfine splitting typical of 55 Mn nucleus, with g values of 2.144 and 2.082 at 25 °C and-196 °C respectively and hyperfine coupling constant of 93.47. The electrochemical studies of the complexes revealed two redox couples for complexes 1 and 3 at a potential range of-0.4 to 0.5 V and-0.29 to 0.42 V respectively with each redox couple associated with a sequential single electron transfer process corresponding to the Mn II /Mn III and Mn III /Mn IV metal center redox process. Complex 1 exhibited one redox couple at 0.5 to 1.2 V potential corresponding to metal center Mn II /Mn III redox process. All the complexes exhibited diffusion controlled behaviour at increase scan with the ratio of cathodic to anodic peak current approximately a unity.