SYNTHESIS, CHARACTERIZATION AND CRYSTAL-STRUCTURE OF (C3H5N2)2[SN2(NO3)4- (MU-OH)2ME4], A DI-MU-HYDROXO-BRIDGED COMPOUND WITH HEPTACOORDINATED TIN(IV)

[Sn2(NO3)2(mu-OH)2Me4] reacts with imidazole in nitric acid media to g ive (C3H5N2)2[Sn2(NO3)4(mu-OH)2Me4], the structure of which was determ ined by X-ray diffraction and refined to R = 0.032 using 1711 observed reflections. The compound is monoclinic, space group P2(1)/c, with a = 9.315(l), b = 16.107(5), c = 8.147(2) angstrom, beta = 101.94(1)-deg rees, Z = 2. The crystal consists of imidazolium [C3H5N2]+ Cations and [Sn2(NO3)4(mu-OH)2Me4]2-anions with the imidazolium rings hydrogen-bo nded to nitrate groups of neighbouring units and to the hydroxyl bridg ing groups of the anion. Each hydroxyl group is also hydrogen bonded t o one nitrate group of a neighbouring anion. In the anion each tin ato m is seven-coordinated to two methyl groups, one asymmetrically bident ate nitrate anion, one monodentate nitrate anion and two bridging hydr oxyl groups. IR and Mossbauer data are discussed on the basis of the a bove coordination scheme.