A novel two-dimensional framework based on unprecedented cadmium(II) chains

Abstract

The bent ligand 4-[(1H-1,2,4-triazol-1-yl)methyl]benzoic acid (HL) has been used to create the novel two-dimensional coordination polymer poly[mu(2)-aqua-mu(2)-chlorido-{mu(2)-4-[(1H-1,2,4-triazol-1-yl)methyl]benzoato}cadmium(II)], [Cd(C(10)H(8)N(3)O(2))Cl(H(2)O)](n), under hydrothermal reaction of HL with cadmium chloride. The crystallographically unique Cd atom is seven-coordinated in an approximately pentagonal-bipyramidal environment of two carboxylate O atoms, two water O atoms, two Cl atoms and one triazole N atom. A notable feature is the presence of zigzag ...Cd...Cd... inorganic chains, in which neighboring Cd(II) ions are doubly bridged by pairs of mu(2)-Cl atoms and mu(2)-H(2)O ligands in an alternating fashion. To the authors' knowledge, this is the first example containing this bridging mode in a cadmium(II) framework. The chains are connected to one another through the bridging L(-) ligand into a two-dimensional undulating network. All of the two-dimensional nets stack exactly together in an ...AA... stacking sequence along the crystallographic b axis. Neighboring layers are further linked into a three-dimensional framework via interlayer hydrogen-bonding interactions.