The novel (mu-alkoxo)bis(mu-carboxylato)diruthenium complex K[Ru(2)(dhpta)(mu-O(2)C-p-ZnTPP)(2)] 3 was prepared by simple ligand substitution reaction. Strong antiferromagnetic interaction between two Ru(III) ions of 3 was observed with a coupling constant of -425 approximately -404 cm(-1). The cyclic voltammogram of 3 can be explained in terms of superposition of those of ZnTPP-p-CO(2)H and K[Ru(2)(dhpta)(mu-O(2)CPh)(2)] 2, indicating no significant electrochemical interaction. The large conproportionation constant estimated from the reduction potentials for Ru(III)Ru(III) and Ru(II)Ru(III) indicates great stability of the mixed-valence state. The mixed-valence species [Ru(II)Ru(III)(dhpta)(mu-O(2)C-p-ZnTPP)(2)](2-) 4 was prepared by controlled potential electrolysis. The electronic absorption spectrum of 4 was quite similar to that of [Ru(II)Ru(III)(dhpta)(mu-O(2)CCH(3))(2)](2-) which is a typical Class II complex. The fluorescence from the S(2) state of the ZnTPP unit of 3 was significantly (78%) quenched. The electron transfer from the ZnTPP unit to Ru(III) ions in 3 is a plausible mechanism, even though energy transfer could not be ruled out completely. The free energy change for electron transfer, Delta G(CS), was estimated to be ca.-1.1 eV, which is similar to typical values for the reorganization energy lambda in polar solvents. Hence, the electron transfer scheme is situated almost at the top of the Marcus parabola, enabling ultrafast electron transfer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.