Synthesis, structure and redox properties of Ru(η-C5H5)(PPh3)2 (O2CR)

552-555Cyclopentadienyl-bis(triphenylphosphine) carboxylatoruthenium(II) compounds, Ru(η- C5H5)(PPh3)2(O2CR) have been prepared by reacting Ru(η-C5H5)(PPh3)2Cl and AgO2CR [R=Me, C6H4-p-X (X = H, Me, OMe, NO2 and Cl)] in benzene. The 18-electron compounds are moderately stable and contain a unidentate carboxylato ligand. Cyclic voltammetry of these compounds shows the presence of a one-electron ruthenium(II)/ruthenium(m) couple near 0.6V (vs SCE) in CH2Cl2. The half-wave potentials follow the Hammett linear free energy relationship when plotted against the σ-values of the substituents