Linkage and redox isomerism in ruthenium complexes of catecholate, semiquinone, and o-acylphenolate ligands derived from 1,2-dihydroxy-9,10-anthracenedione (alizarin) and related species: Syntheses, characterizations, and photophysics

The complexes Ru(CO)(2)L-2(AL-2H) (AL = alizarin; L = PPh3, PCyc(3), PBu3, P(m-NaSO3C6H4)(3)), Ru(CO)(dppe)(PBu3)(AL-2H), and RuH(CO)L-2(AL-H) (L = PP h3, PCyc(3)), and Ru(CO)(2)L-2(AR-2H) (AR = anthrarobin; L = PBu3) were pre pared by reactions of Ru-3(CO)(12), L, and AL, and the complexes RuH(CO)(PP h3)(2)(AL-H), RuH(CO)(PPh3)(2)(QN-H) (QN = quinizarin), and RuH(CO)(PPh3)(2 )(LQN-H) (LQN = leucoquinizarin) are prepared by reactions of RuH2(CO)(PPh3 )(3) with AL or QN. The AL-2H and AR-2H ligands act as 1,2-catecholates, wh ereas the AL-H, QN-H, LQN-H ligands are 1,9-o-acylphenolate ligands. RuH(CO )(PPh3)(2)(AL-H) is characterized by X-ray crystallography. The electrochem istry of these complexes is examined, and the semiquinone complexes [Ru(Co) (2)L-2(AL-2H)](+) (L = PPh3, PCyc(3), PBu3) and [Ru(CO)(dppe)(PBu3)(AL-2H)] (+) are generated by chemical oxidation and were characterized by EPR and I R spectroscopy. The photophysical properties are also reported.