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

Abstract

MX⋯HN⁺ hydrogen bond synthons have been exploited in preparation of crystalline salts [4,4′-H₂bipy][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′-H₂bipy]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.