Organic-inorganic hybrid solids:: control of perhalometallate solid state structures

MX . . . HN+ hydrogen bond synthons have been exploited in preparation of crystalline salts [4,4'-H(2)bipy][MX4] [X=Cl, M=Pd, Pt, Co, Zn, Hg, Mn, Cd and Pb; X=Br, M=Pd, Co, Zn and Mn]. In these salts three structural forms for the halometallate species are observed: mononuclear square planar (M=Pd, Pt) or tetrahedral (M=Co, Zn, Hg) and polymeric cis edge-sharing octahedral (M=Mn, Cd, Pb). These correspond to three structural motifs which form the basis of the crystal structures formed in their [4,4'-H(2)bipy](2+) salts: ribbon polymer (M=Pt, Pd); herring-bone packing of cyclic dimers (M=Co, Zn, Hg); layer cross-linked polymers [{MX4}(n)](2n-) (M=Mn, Cd, Pb). The factors controlling the structures adopted, the hierarchy of intermolecular interactions present in these crystals and the principles that may be inferred and exploited further are considered.