2 DIFFERENT CRYSTAL FORMS OF CIS-DIAMMINEBIS(PYRAZOLE)PLATINUM(II) DINITRATE

The crystal structures of cis-diamminebis(pyrazole)platinum(II) dinitr ate, cis-[Pt(NH3)(2)(C3H4N2)(2)](NO3)(2), (1), and cis-diamminebis(pyr azole)platinum(II) dinitrate pyrazole solvate, cis-[Pt(NH3)(2)(C3H4N2) (2)](NO3)(2).C3H4N2, (2), have been determined by X-ray diffraction. I nterestingly, compound (1) crystallizes in the centrosymmetric space g roup P2(1)/n, while compound (2) somehow crystallizes in the non-centr osymmetric space group P2(1). In both (1) and (2), the two coordinated pyrazole planes are twisted with respect to the Pt coordination plane s at angles of between 46.0(9) and 60.5(4)degrees. The free pyrazole m olecule contained as a crystal solvent in compound (2) forms a strong hydrogen bond [2.82(1) Angstrom] with one of the two coordinated pyraz ole ligands. In each crystal, the packing is electrostatically stabili zed through hydrogen bonds formed between the nitrate O atoms and the ammine and pyrazole ligands.