Copper(II) chloride and bromide complexes with 2-methyl-2H-tetrazol-5-amine: an X-ray powder diffraction study

The complex catena-poly[[dibromidocopper(II)]-bis(mu-2-methyl-2H-tetrazol-5-amine)-kappa(2)N(4):N(5);kappa(2)N(5):N(4)], [CuBr(2)(C(2)H(5)N(5))(2)](n), (I), and the isotypic chloride complex catena-poly[[dichloridocopper(II)]-bis(mu-2-methyl-2H-tetrazol-5-amine)-kappa(2)N(4):N(5);kappa(2)N(5):N(4)], [CuCl(2)(C(2)H(5)N(5))(2)](n), (II), were investigated by X-ray powder diffraction at room temperature. The crystal structure of (I) was solved by direct methods, while the Rietveld refinement of (II) started from the atomic coordinates of (I). In both structures, the Cu atoms lie on inversion centres, adopting a distorted octahedral coordination of two halogen atoms, two tetrazole N atoms and two 5-amine group N atoms. Rather long Cu-N(amine) bonds allow consideration of the amine group as semi-coordinated. The compounds are one-dimensional coordination polymers, formed as a result of 2-methyl-2H-tetrazol-5-amine ligands bridging via a tetrazole N atom and the amine N atom. In the polymeric chains, adjacent Cu atoms are connected by two such bridges.