Synthesis and redox behavior of ruthenocene-terminated oligoenes: characteristic and stable two-electron redox system and lower potential shift of the two-electron oxidation wave with elongating conjugation.

Ruthenocene-terminated butadienes and hexatrienes were prepared by the Wittig reaction of 3-ruthenocenyl-2-propenals with ruthenocenylmethylphosphonium salts and the Mukaiyama coupling of the propenals, respectively. Cyclic voltammetry of these complexes indicated that they were involved in a stable two-electron redox process. The oxidation potentials for ruthenocene-terminated oligoenes shifted progressively to lower potential with the increasing CH==CH units as follows: Rc--Rc (0.

Kinetic Study on the Substitution of Dimethylacetamide for the Terminal Aqua Ligands in the Trinuclear Chromium(III) Complexes [Cr(3)(&mgr;(3)-O)(&mgr;-RCO(2))(6)(H(2)O)(3)](+) (R = H, CH(3), CH(3)CH(2), CH(2)Cl, CHCl(2), CH(3)OCH(2), (CH(3))(3)C, CH(2)ClCH(2), (CH(3)CH(2))(2)CH). Elucidation of the Mechanism from the Activation Volumes and the Substituent Effects of Bridging Carboxylate Ligands.

The substitution of dimethylacetamide (dma) for the terminal aqua ligands in the carboxylate-bridged trinuclear chromium(III) complex [Cr(3)(&mgr;(3)-O)(&mgr;-RCO(2))(6)(H(2)O)(3)](+) (R = H, CH(3), CH(3)CH(2), CH(2)Cl, CHCl(2), CH(3)OCH(2), (CH(3))(3)C, CH(2)ClCH(2), (CH(3)CH(2))(2)CH) in dma was kinetically studied by UV-visible absorption at 25-50 degrees C and 0.1-232 MPa. The time course is uniphasic over all three steps of the ligand replacement.