Synthesis, spectroscopic characterization and thermal behavior of cadmium(II) complexes of S-methyldithiocarbazate (SMDTC) and S-benzyldithiocarbazate (SBDTC): X-ray crystal structure of [Cd(SMDTC)3] · 2NO3

Two new cadmium(II) complexes of the empirical formulae [Cd(SMDTC)3] · 2NO3 (1) and [Cd(SBDTC)2] · 2NO3 (2) have been synthesized and characterized by elemental analyses, UV–Vis, IR, 1H NMR and TGA techniques. In complex 1, the six coordination sites around cadmium are occupied by three neutral SMDTC molecules with N and S donor atoms from each ligand molecule, whereas in complex 2 the cadmium center is four coordinated with two relatively larger SBDTC ligands chelating with N and S donor atoms in the neutral thione form. In the solid state, thermal gravimetric analysis shows that both complexes are relatively volatile in nature and undergo facile thermal decomposition above 120 °C to form the metal sulfide followed by stepwise loss of ligand molecules. The crystal and molecular structure of complex 1 has been established by the X-ray diffraction method. The central cadmium(II) atom has an octahedral geometry with three five-membered chelate rings formed by SMDTC ligands. The crystal structure consists of parallel layers of cations and anions. The SMDTC molecules in cations are arranged with their N donor groups directed towards the anion layer in an alternating fashion and form hydrogen bonds with the O atoms of the anion.

The reaction of S-methyl dithiocarbazate (SMDTC) and S-benzyl dithiocarbazate (SBDTC) with Cd(NO3)2. 4H2O gave monomeric 1:2 complexes [Cd(SMDTC)3](NO3)2 and [Cd(SBDTC)2](NO3)2 respectively in which the ligands, in its neutral thione form, adopt bidentate chelating bonding mode to the metal center. The coordination geometry around cadmium(II) in [Cd(SMDTC)3](NO3)2 is distorted octahedral, as obtained by X-ray diffraction study whereas [Cd(SBDTC)2](NO3)2 is expected to be tetrahedral.Figure optionsDownload as PowerPoint slide