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

The reactions of zinc(II)chloride with 2,3-di-methyl-pyrazine (C6H8N2) in different ratios in aceto-nitrile lead to the formation of [ZnCl2(C6H8N2)2] (1) and [ZnCl2(C6H8N2)] n (2). The asymmetric unit of 1 consists of one Zn cation located on a twofold rotation axis, one chloride anion and one 2,3-di-methyl-pyrazine ligand that occupy general positions. In compound 2 the asymmetric unit is built up of one zinc cation, two chloride anions and one 2,3-di-methyl-pyrazine ligand that are located in general positions in the uncommon trigonal space group P32. In compound 1, the Zn cations are tetra-hedrally coordinated by two chloride anions and two 2,3-di-methyl-pyrazine ligands forming discrete complexes. These complexes are arranged in columns that proceed along the c-axis direction. The Zn cations in 2 are also tetra-hedrally coordinated by two chloride anions and two 2,3-di-methyl-pyrazine ligands but linked via the bridging 2,3-di-methyl-pyrazine ligands into helical infinite chains that propagate along the c-axis direction. Powder X-ray diffraction measurements indicate that both compounds were obtained as pure crystalline phases.