Electronic structure and catalytic aspects of [(trpy)(Cl)Ru(L)]n incorporating potential non-innocent ligands, L-: 9-Oxidophenalenone and trpy: 2,2′:6′,2-terpyridine

The title complex [(trpy)(Cl)Ru-II(L)] (1) incorporating potential redox non-innocent ligands, L- = 9-oxidophenalenone and trpy = 2,2':6',2 ''-terpyridine has been structurally characterized. The crystal structure of 1 establishes the distorted octahedral arrangement, meridional coordinating mode of trpy and delocalized C-O bond distances of coordinated L-. Compound 1 displays two one-electron oxidations at E-298(0), 0.12 V (Ox1) and 1.32 V (Ox2) and one reduction, -1.58 V versus SCE. Predominantly ruthenium based first oxidation (Ox1) and L based second oxidation (Ox2) lead to the valence configurations of [(trpy)(Cl)Ru-III(L-)](+) (1(+)) and [(trpy)(Cl)Ru-III(L-center dot)](2+) (1(2+)), respectively. The antiferromagnetic coupling of spins on Ru(III) (low-spin, t(2g)(5)) and L-center dot develops a singlet (S = 0) ground state in 1(2+). The reduction, however, occurs at the trpy site. The electronic transitions in 1 and 1(+) could be assigned based on the TD-DFT calculations. Interestingly, 1 has been established to be an efficient pre-catalyst for the oxidative cleavage of alkenes to carbonyl derivatives. (C) 2012 Elsevier Ltd. All rights reserved.