A ruthenium bridge in fullerene-ferrocene arrays: synthesis of [Ru(C60Me5)R(CO)2] (R=C6H4Fc, C identical withCFc) and their charge-transfer properties.

New fullerene-ferrocene arrays, [Ru(C(60)Me(5))(C(4)H(6)Fc)(CO)(2)] (Fc=ferrocenyl) and [Ru(C(60)Me(5))(CCFc)(CO)(2)], in which the ruthenium complex functions as a conjugative bridge, were synthesized by the reaction of [Ru(C(60)Me(5))Cl(CO)(2)] with FcC(6)H(4)MgBr and FcCCLi, respectively. These compounds were investigated by electrochemical measurement, single-crystal X-ray structural analysis, and photophysical measurement. Upon photoirradiation, the former compound was converted rapidly into the corresponding triplet state in toluene (tau(singlet)=21 ps), whereas the charge-separated state was predominant in THF (tau(singlet)=10.5 ps; tau(CS)=355 ps). The latter compound, on the other hand, formed the charge-separated state in both toluene and THF (tau(singlet)=3.0 ps; tau(CS)=152 ps). Thus, the structural difference between the phenylene and acetylene bridges in 1 and 2, respectively, was found to change the outcome of the photophysical processes.