Organic-inorganic hybrid mixed-halide Zn(II) and Cd(II) tetra-halometallates with the 2-methyl-imidazo[1,5-a]pyridinium cation.

Three isomorphous 0-D hybrid salts, namely, 2-methyl-imidazo[1,5-a]pyridinium tri-chlorido-iodido-zincate(II), (C(8)H(9)N(2))(2)[ZnCl(3.19)I(0.81)] or [L](2)[ZnCl(3.19)I(0.81)], (I), 2-methyl-imidazo[1,5-a]pyridinium di-bromido-dichlorido-cadmate(II), (C(8)H(9)N(2))(2)[CdBr(2.42)Cl(1.58)] or [L](2)[CdBr(2.42)Cl(1.58)], (II), and 2-methyl-imidazo[1,5-a]pyridinium tri-chlorido-iodido-cadmate(II), (C(8)H(9)N(2))(2)[CdCl(3.90)I(0.10)] or [L](2)[CdCl(3.90)I(0.10)], (III), are assembled from discrete 2-methyl-imidazo[1,5-a]pyridinium cations, L (+), and mixed-halide tetra-halometallate anions. In the three structures, there are two crystallographically non-equivalent cations that were modelled as being rotationally disordered by 180°. In the lattices of the three compounds, a disordered state exists involving partial substitution of Cl by I for sites 2-4 in (I), Br by Cl for all four sites in (II) and Cl by I for site 2 in (III). In the solid state, the organic and inorganic sheets alternate parallel to the bc plane in a pseudo-layered arrangement. In the organic layer, pairs of centrosymmetic-ally related trans-oriented cations form π-bonded chains. The adjacent tetra-halometallate anions in the inorganic layer show no connectivity with the shortest M⋯M separations being greater than 7†à . A variety of C-H⋯X-M (X = Cl, Br, I) contacts between the organic and inorganic counterparts provide additional structural stabilization. The title structures are isomorphous with the previously reported structures of the chloride analogues, [L](2)[ZnCl(4)] and [L](2)[CdCl(4)].