Copper(II) and cadmium(II) isothiocyanate coordination polymers with 4,4'-bi-1,2,4-triazole.

The coordination polymers catena-poly[[[(4,4'-bi-1,2,4-triazole-kappaN(1))bis(thiocyanato-kappaN)copper(II)]-mu-4,4'-bi-1,2,4-triazole-kappa(2)N(1):N(1')] dihydrate], {[Cu(NCS)(2)(C(4)H(4)N(6))(2)].2H(2)O}(n), (I), and poly[tetrakis(mu-4,4'-bi-1,2,4-triazole-kappa(2)N(1):N(1'))bis(mu-thiocyanato-kappa(2)N:S)tetrakis(thiocyanato-kappaN)tricadmium(II)], [Cd(3)(NCS)(6)(C(4)H(4)N(6))(4)](n), (II), exhibit chain and two-dimensional layer structures, respectively. The differentiation of the Lewis acidic nature of Cu(II) and Cd(II) has an influence on the coordination modes of the triazole and thiocyanate ligands, leading to topologically different polymeric motifs. In (I), copper ions are linked by bitriazole N:N'-bridges into zigzag chains and the tetragonal-pyramidal CuN(5) environment is composed of two thiocyanate N atoms and three triazole N atoms [basal Cu-N = 1.9530 (18)-2.0390 (14) A and apical Cu-N = 2.2637 (15) A]. The structure of (II) contains two types of crystallographically unique Cd(II) atoms. One type lies on an inversion center in a distorted CdN(6) octahedral environment, with bitriazole ligands in the equatorial plane and terminal isothiocyanate N atoms in the axial positions. The other type lies on a general position and forms centrosymmetric binuclear [Cd(2)(mu-NCS-kappa(2)N:S)(2)(NCS)(2)] units (tetragonal-pyramidal CdN(4)S coordination). N:N'-Bridging bitriazole ligands link the Cd centers into a flat (4,4)-network.