Thermal stability of mixed-valent diruthenium (II,III) carboxylates

The thermal stability of mixed-valent diruthenium carboxylates, Ru2II,III (O2CR)4X, where RCO2− are the equatorial carboxylates and X− is the axial ligand (halide or carboxylate anion) was investigated. The nature of the axial ligands determines two decomposition pathways, while the equatorial carboxylate plays a minor role. The general behavior involves the reduction of the bimetallic center to Ru0. The halocomplexes (X−=halide) decompose in just one complex step. The pentacarboxylates (X−=CH3(CH2)n−2CO2−) have a two-step mechanism being the intermediate product Ru2II,II (O2C(CH2)n−2CH3)4. The influence of the liquid crystalline phase was explored.