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

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.