Organic–Inorganic Hybrids Constructed from Mixed-Valence Multinuclear Copper Complexes and Templated by Keggin Polyoxometalates

Abstract

Five organic–inorganic hybrids containing mixed–valence multinuclear copper complexes and Keggin polyoxometalates, [CuI5CuII3(ptz)8(H2O)][HSiW12O40] (1), [CuI10CuII2(ptz)8(Cl)3][PW12O40] (2), [CuI2CuII4(ptz)6(OH)(H2O)2][PW12O40]·2H2O (3), CuI2CuII5(ptz)6(OH)2SiW12O40·6H2O (4), and [CuI2CuII5(ptz)6][PMoV3MoVI9O40]·8H2O (5) (ptz = 5-(2-pyridyl)-tetrazole), were hydrothermally synthesized and structurally characterized. Compound 1 exhibits a three-dimensional (3D) network that features unprecedented double chains consisting of tetranuclear Cu clusters. Compound 2 displays a 3D network that has unusual Cl-centered hexanuclear Cu clusters and Cl-bridged tetranuclear Cu units. Compound 3 shows a 3D supramolecular network extended by two-dimensional (2D) grid-like sheets which are composed of mixed-valence multinuclear copper chains and PW12 polyanions. Isostructural compounds 4 and 5 exhibit a 3D network consisting of 2D ladder-like copper–ptz layers and SiW12 (PMo12 in 5) polyanions. The roles of copper ions with different oxidation states and ptz ligands with different coordination modes in the construction of the copper–ptz frameworks are discussed. Their electrochemical properties were investigated as well.