Syntheses and crystal structures of bis-(2,3-di-methyl-pyrazine-κN)di-iodido-cadmium(II) and catena-poly[[di-iodido-cadmium(II)]-μ-2,3-di-methyl-pyrazine-κ2 N 1:N 4].

The reaction of cadmium iodide with 2,3-di-methyl-pyrazine leads to the formation of two compounds with the compositions [CdI2(C6H8N2)2] or [CdI2(2,3-di-methyl-pyrazine)2] (1) and [CdI2(C6H8N2)] n or [CdI2(2,3-di-methyl-pyrazine)] n (2). The asymmetric unit of 1 is built up of one CdII cation as well as two iodide anions and two 2,3-di-methyl-pyrazine ligands representing complete mol-ecules. The CdII cations are tetra-hedrally coordinated, forming discrete complexes that are connected via weak C-H⋯I inter-actions. The asymmetric unit of 2 consists of one CdII cation and two crystallographically independent iodide anions that are located on a crystallographic mirror plane, as well as one 2,3-di-methyl-pyrazine ligand that is located on a twofold rotation axis. The CdII cations are tetra-hedrally coordinated by two iodide anions and two 2,3-di-methyl-pyrazine ligands into corrugated chains. As in 1, inter-molecular C-H⋯I inter-actions are observed. Comparison of the experimental powder patterns with those calculated from single-crystal data proves that pure compounds have been obtained. The crystal structures are compared with those of related MX 2 (M = Zn, Cd, X = Cl, Br, I) coordination compounds with pyrazine and 2,3-di-methyl-pyrazine, that are reported in the literature.