Abstract
The reaction of zinc iodide with 2,3-di-methyl-pyrazine (C(6)H(8)N(2)) in ethanol leads to the formation of [ZnI(2)(C(6)H(8)N(2))] (n) (1), that according to powder X-ray diffraction was obtained as a pure phase. When the same reaction was performed in a mixture of ethanol and water as solvent, a few crystals of [ZnI(2)(C(6)H(8)N(2))(H(2)O)]·0.5C(6)H(8)N(2)·0.5H(2)O (2) were serendipitiously obtained in a mixture with compound 1 as the major phase. The asymmetric unit of 1 consists of one zinc cation, two crystallographically independent iodide anions and one 2,3-di-methyl-pyrazine ligand all of them located in general positions. In the extended structure, the Zn cations are tetra-hedrally coordinated by two iodide anions and two symmetry-related 2,3-di-methyl-pyrazine ligands and are linked by bridging 2,3-di-methyl-pyrazine ligands into helical chains that proceed along the c-axis direction in the uncommon space group P3(2). Within these chains, intra-chain C-H⋯I hydrogen bonding is observed. The asymmetric unit of 2 consists of two crystallographically independent [ZnI(2)(C(6)H(8)N(2))(H(2)O)] complexes as well as one water mol-ecule and one none-coordinating 2,3-di-methyl-pyrazine ligand. In the complexes, the Zn cations are tetra-hedrally coordinated by two iodide anions, one 2,3-di-methyl-pyrazine ligand and one water mol-ecule. These complexes are packed in such a way that cavities are formed, which are filled by water and 2,3-di-methyl-pyrazine solvate mol-ecules that are hydrogen bonded to each other.