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 Å. 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 ].