Piperazine-Bridged Homodinuclear Transition Metal Complexes

Piperazine-bridged transition metal complexes of the type [M(etdtc)] 2 ppzdtc and [M 1 (etdtc) 2 ] 2 ppzdtc [where M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II), M 1 = Cr(III), Fe(III), etdtc = (S 2 NC 5 H 10 ) and ppzdtc = [S 2 C(NCH 2 CH 2 ) 2 CS 2 ] have been synthesised and characterised by elemental analyses, magnetic susceptibility measurements, TGA/DSC, IR and electronic spectroscopy and conductivity measurements. The presence of only one (C–S) stretching frequency at around 1000 cm −1 supports symmetrical bonding of the dithiocarbamato-moiety. The low molar conductance value of the complexes in DMSO at 25 °C indicates their non-electrolytic behaviour. Thermogravimetric analysis showed only two-step, simple pyrolysis. The decomposition is generally exothermic, leading to the formation of metal sulfide as the final product. The complexes of divalent metal ions appear to be tetrahedral, excepting Cu(II) and Ni(II) which are square-planar, while those of trivalent metal ions are octahedral, which is also corroborated from their electronic spectra and magnetic moment data.