SYNTHESIS AND CHEMICAL CHARACTERIZATION OF 2-METHYLPYRIDINIUM SALTS OF PLANAR NICKEL(II), PALLADIUM(II) AND PLATINUM(II) 1,2-DITHIOOXALATO-S,S' COMPLEXES - CRYSTAL AND MOLECULAR-STRUCTURE OF BIS(2-METHYLPYRIDINIUM) BIS(1,2-DITHIOOXALATO-S,S')NICKELATE(II)

Microcrystalline powders of the complexes (HC6H7N)2[Ni(S2C2O2)2] (1), (HC6H7N)2[Pd(S2C2O2)2] (2) and (HC6H7N)2[Pt(S2C2O2)2](3) were obtained by reaction of 2-methylpyridinium hydrochloride and the corresponding K2[M(S2C2O2)2] salts in aqueous solution. These compounds were charac terized by elemental analysis, IR and UV-vis spectroscopies, thermal a nalysis (TG, DTG and DTA) and X-ray diffraction techniques. Single cry stals of compound 1 were obtained by recrystallization in N,N-dimethyl formamide and its crystal structure was determined from single-crystal X-ray diffraction. The crystal structure consists of mixed layers of quasi-planar complex [Ni(S2C2O2)2]2- anions and 2-methylpyridinium cat ions held together by electrostatic interactions, an extensive network of hydrogen bonds of the types N-H...O and C-H...O and anion-cation p i-pi interactions.