Mixed-valence μ3-oxo-centered triruthenium cluster [Ru3(II,III,III)(μ3-O)(μ-CH3CO2)6(H2O)3]·2H2O: Synthesis, structural characterization, valence-state delocalization and catalytic behavior

Abstract The oxo-centered, trinuclear, mixed valence [Ru 3 (II,III,III) O(CH 3 CO 2 ) 6 (H 2 O) 3 ]·2H 2 O ( 2 ) acetate complex has been prepared with high yield through reduction of [Ru 3 (III,III,III) O(CH 3 CO 2 ) 6 (CH 3 OH) 3 ]·CH 3 CO 2 precursor compound in presence of muccic acid under hydrothermal conditions. The crystalline trinuclear oxo-cluster has been obtained as crystalline powder and characterized by single-crystal and powder X-ray diffraction, elemental analysis, SEM, TGA, IR spectroscopy. Complex 2 composes of μ 3 -oxocentered trinuclear ruthenium array and exhibits the oxidation state delocalization between three Ru atoms at 293 K. Accurate single-crystal analysis along with valence bond calculations reveal trapped-valence state delocalization at room temperature, whereas three-site relaxation occurs at 100 K leading to Ru(II) and Ru 2 (III) formal states. Moreover, the mixed valence of Ru II Ru 2 III unit in compound 2 has been confirmed by XANES spectroscopy. The catalytic behavior of oxo-centered triruthenium complex 2 has been examined in hydration of nitriles and isomerization of allylic alcohols reactions both realized in aqueous media.