STRUCTURES OF 2-AMINO-3-METHYLPYRIDINIUM BIS(1,2-DITHIOOXALATO-S,S')METALLATES(II) (M = NI, PD AND PT)

Three 2-amino-3-methylpyridinium salts of planar inorganic dithiooxalato anions, (C6H9N2)2[Ni(S2C2O2)2] (1), (C6H9N2)2[Pd(S2C2O2)2] (2) and (C6H9N2)2[Pt(S2C2O2)2] (3) have been prepared. Complexes (1) and (3) are isomorphous with (2) which crystallizes in the monoclinic space group P2(1)/c with Z = 2 so that the anion straddles a crystallographic centre of symmetry. The crystal structure of (2) is built by mixed layers of quasi-planar complex [Pd(S2C2O2)2]2- anions and (C6H9N2)+ cations linked through electrostatic interactions, an extensive network of hydrogen bonds of types N-H...O and C-H...O, and weak pi-pi interactions. It is clear that the packing in this type of compound is affected by the cation shape and by the hydrogen-bonding network since it is the nature of the cation rather than the metal which determines the geometry of the interactions.