Hydrothermal Synthesis,Structural Investigation and Characterization of an Organic-inorganic Hybrid, [Co（BIIM）3]2H[BW12040]·7H2O

An organic-inorganic hybrid based on a-Keggin-typed [BWI2040]5- anionic cluster, [Co（BIIM）3]2H[BWx2040]＇7H20 （BIIM = 2,2＂-biimidazole）, was hydrothermally synthesized and structurally characterized by thermogravimetric analysis, IR and UV spectra. The title compound crystallizes in monoclinic, space group P21/n with a = 12.3490（10）, b = 33.270（3）, c = 18.9660（16） A, β = 105.9950（10）°, V= 7490.5（11） A3, C36HsoBCo2N24047W12, Mr = 3905.80, Dc = 3.45 l g/cm3, μ（MoKa） = 18.886 rnm-1, F（000） = 6972, Z = 4, S = 1.004, the final R = 0.0404 and wR = 0.0914 for 14683 observed reflections （1 〉 2tr（/））. The compound consists of two isolated [Co（BIIM）3]2＋ cations and one [BW12040]5 anion, in which each Co2＋ ion is coordinated by six N atoms from three BIIM ligands displaying a regular CoN6 octahedron. These components are finally linked together via N-H...O（polyoxometalate and wate） hydrogen bonds into a two-dimensional framework. Full investigation of the intermolecular interactions by Hirshfeld surface and fingerprint plots clearly indicates that there are rare W--Oterminal···πimidazole ring interactions which cooperate with the classical N-H···O hydrogen bonds to stabilize the structural packing.