Synthesis, Characterization, and Substituent Effects of Binuclear Ruthenium Vinyl Complexes [RuCl(CO)(PMe3)3]2(μ-CH=CH-Ar-CH=CH)

A series of binuclear ruthenium vinyl complexes [RuCl(CO)(PMe3)(3)](2)(mu-CH=CH-Ar-CH=CH) (Ar = C6H4 (6a), C6H3CH3 (6b), C6H3OCH3 (6c), C6H3F (6d), C6H3Cl (6e), C6H3Br (6f), C6H3CN (6g), C6H3NO2 (6h), C6H2(CH3)(2)-2,5 (6i), C6H2(OCH3)(2)-2,5 (6i), C6H2(F)(2)-2,5 (6k), C6H2(CF3)(2)-2,5 (6l), and C6H3CF3 (6m)) have been prepared. The respective products have been characterized by elemental analyses, NMR spectrometry, and UV/vis spectrophotometry. The structures of 6h, 6i, and 6j have been established by X-ray crystallography. Electrochemical studies have revealed that intermetallic electron communication between the two Ru centers may be fine-tuned by modification of the bridging spacers, that is, by introducing one or two substituent groups on the 1,4-diethenylphenylene bridge. Electron-releasing substituents have been found to facilitate electron communication between the two metal centers.