Spectroelectrochemical investigation of platinum(II) complexes containing bidentate nitrogen and sulphur donor ligands

Cyclic and Linear Sweep Voltammetry techniques were applied to enlighten the electrochemical behaviour of 5,6-di-2-thienyl-2,3-dihydropyrazine coordinated platinum complexes, [Pt(NH3)Cl(L)]Cl.7,5H2O, [PtCl2(L)].H2O and [Pt(L)2]Cl2.0,5H2O in asymmetric, bis and cis geometry, respectively in DMF (Dimethyl formamide) at platinum electrode vs Ag/AgCl. Constant potential electrolysis of the platinum(II) complexes were carried out their oxidation peak potential and the spectral changes recorded in situ by using electronic absorption spectrophotometer in order to reveal the mechanism of the oxidation reaction. Electro oxidation of free ligand at 1.24 V generates a dimer. Elongated electrolysis of the ligand, on the other hand, yields the polymer of the thenyl pyrazine. Electrochemical oxidation of platinum complexes produce a radicalic complex cation, which is stabilized in asymmetric and cis geometries but unstable in bis geometry. Electrochemical reduction of the ligand and the platinum complexes suggested that the reduction of all these compounds involve pyrazine ring.