Synthesis and crystal structure of catena-poly[[[aqua-(2,3-di-methyl-pyrazine-κN)cadmium(II)]-di-μ-bromido] 2,3-di-methyl-pyrazine monosolvate hemihydrate].

Crystals of the title compound, {[CdBr2(C6H8N2)(H2O)]·C6H8N2·0.5H2O} n (C6H8N2 = 2,3-di-methyl-pyrazine), were obtained accidentally by the reaction of cadmium bromide with 2,3-di-methyl-pyrazine in water. The asymmetric unit consists of one Cd cation, two bromide anions, one 2,3-di-methyl-pyrazine ligand, one non-coordinating 2,3-di-methyl-pyrazine mol-ecule, and one water mol-ecule in general positions as well as an additional water mol-ecule that is located on a twofold rotation axis. The cadmium cations are octa-hedrally coordinated by four bromide anions, one 2,3-di-methyl-pyrazine ligand and one water mol-ecule, and are linked by pairs of μ-1,1-bridging bromide anions into chains that propagate in the a-axis direction. These chains are further connected into layers by inter-molecular hydrogen bonding. The coordinated water ligand is hydrogen bonded to the 2,3-di-methyl-pyrazine, and the water solvate mol-ecule and the 2,3-di-methyl-pyrazine mol-ecules of crystallization are linked by O-H⋯N hydrogen bonding via the water solvate mol-ecules into chains along the c-axis direction. The water solvate mol-ecule therefore acts as donor for two O-H⋯N and as acceptor for two O-H⋯O hydrogen bonds.