SYNTHESIS, STRUCTURE AND REDOX PROPERTIES OF (MU-OXO)BIS(MU-CARBOXYLATO)DIRUTHENIUM(III) COMPLEXES CONTAINING 3 DIFFERENT TERMINAL LIGANDS

Blue coloured, unstable, essentially diamagnetic and non-electrolytic diruthenium(III) complexes of the formulation [Ru2O(O2CR)4(en)2(PPh3)2] were prepared by reacting [Ru2O(O2CR)4(PPh3)2] with 1,2-diaminoethane (en) in CH2Cl2 (R = C6H4-p-X; X = H, Me and OMe). The molecular structure of the complexes is proposed as [{(eta1-O2CR)(eta1-en)(PPh3)Ru}2(mu-O)(mu-O2CR)2] based on the H-1 NMR spectral data. The electronic spectra of the complexes display a band near 569 nm with a shoulder at 630 nm. In CH2Cl2-0.1 M [Bun4N]ClO4, the complexes exhibit redox couples Ru2III,III/Ru2III,IV and Ru2III,IV/Ru2IV,IV near 0.1 and 1.2 V (vs SCE), respectively. The potentials are the lowest among diruthenium(III) complexes with a similar core structure.