Organic-inorganic hybrid mixed-halide ZnII and CdII tetrahalometallates with the 2-methylimidazo[1,5-a]pyridinium cation

Three isomorphous 0-D hybrid salts, namely, 2-methylimidazo[1,5-a]pyridinium trichloridoiodidozincate(II), (C8H9N2)(2)[ZnCl3.19I0.81] or [L](2)[ZnCl3.19I0.81], (I), 2-methylimidazo[1,5-a]pyridinium dibromidodichloridocadmate(II), (C8H9N2)(2)[CdBr2.42Cl1.58] or [L](2)[CdBr2.42Cl1.58], (II), and 2-methylimidazo[1,5-a]pyridinium trichloridoiodidocadmate(II), (C8H9N2)(2)[CdCl3.90I0.10] or [L](2)[CdCl3.90I0.10], (III), are assembled from discrete 2-methylimidazo[1,5-a]pyridinium cations, L+, and mixed-halide tetrahalometallate anions. In the three structures, there are two crystallographically non-equivalent cations that were modelled as being rotationally disordered by 180 degrees. 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 centrosymmetically related trans-oriented cations form pi-bonded chains. The adjacent tetrahalometallate anions in the inorganic layer show no connectivity with the shortest M center dot center dot center dot M separations being greater than 7 angstrom. A variety of C-H center dot center dot center dot 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)[ZnCl4] and [L](2)[CdCl4].

Automated summary

Three isomorphous 0-D hybrid salts consisting of 2-methylimidazo[1,5-a]pyridinium cations and mixed-halide tetrahalometallate anions have been reported. The structures exhibit a pseudo-layered arrangement with alternating organic and inorganic layers. C-H center dot center dot center dot X-M (X = Cl, Br, I) contacts provide additional structural stabilization.