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

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(C10H8N3O2)Cl(H2O)](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 center dot center dot center dot Cd center dot center dot center dot Cd center dot center dot center dot inorganic chains, in which neighboring Cd II ions are doubly bridged by pairs of mu(2)-Cl atoms and mu(2)-H2O 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.