SYNTHESIS, CHEMICAL CHARACTERIZATION, STRUCTURAL DATA AND THERMAL-BEHAVIOR OF 3-METHYLPYRIDINIUM SALTS OF 1,2-DITHIOOXALATO-S,S' COMPLEXES WITH FORMULA (HB)(2)[M(S2C2O2)(2)] (M=NI-II, PD-II AND PT-II)

Microcrystalline powders of three complexes of formula (HC6H7N)(2) [Ni(S2C2O2)(2)] (1), (HC6H7N)(2)[Pd(S2C2O2)(2)] (2) and (HC6H7N)(2)[Pt(S2C2O2)(2)] (3), were synthesized and characterized by elemental analysis, IR and UV-vis spectroscopies, thermal analysis (TG, DTG and DTA) and X-ray powder diffraction techniques. The IR and UV-vis spectra support the presence of the aromatic cation and the complex anion. The three compounds are isostructural, and crystallize in the monoclinic space group P2(1)/n with Z = 2. Thermal studies give evidence that the mechanism and the final solid products are strongly influenced by the atmospheric conditions. The final decomposition products were identified by elemental analysis and the X-ray powder diffraction technique. Thermal decomposition in argon-oxygen atmosphere, gave final residues identified as a mixture of nickel sulphides, oxides and sulphate for 1, metallic palladium and palladium(II) oxide for 2, and platinum(0) for 3. Thermal decompositions in the inert atmosphere yielded nickel(II) sulphide, a mixture of Pd/PdS, and metallic platinum, respectively.