Synthesis, Characterization, and Properties of Anthracene-Bridged Bimetallic Ruthenium Vinyl Complexes [RuCl(CO)(PMe3)3]2(μ-CH=CH-anthracene-CH=CH)

Four anthracene-based bimetallic ruthenium vinyl complexes, in which two ruthenium units are attached at different positions (the 9,10-, 1,5-, 2,6-, and 1,8-positions) of the anthracene moiety, have been synthesized by treating the appropriate anthracene-based ethynes with [RuHCl(CO)(PPh3)(3)]. These bimetallic complexes have been thoroughly characterized by NMR, X-ray diffraction, and elemental analysis. According to the single-crystal X-ray structures, the 2,6-disubstituted ruthenium vinyl complex has a more planar structure compared with the 9,10-disubstituted complex, possibly because it has less steric hindrance. Furthermore, we have investigated the optical electronic properties of these complexes, such as their UV/vis absorption spectra, fluorescence spectra, and electrochemical properties. The optical electronic results indicated that the 2,6-disubstituted ruthenium vinyl complex displayed the strongest fluorescence emission due to the more planar structure of its organic conjugated bridge, and the electrochemical studies showed that the two ruthenium centers displayed obvious differences in electronic communication when they are located at different positions on the anthracene unit, with the 9,10- and 1,8-disubstituted ruthenium vinyl complexes exhibiting better electronic communication and higher stability of the mixed-valence complex than the 1,5- and 2,6-disubstituted complexes.