title: Ce(IV)- and light-driven water oxidation by [Ru(terpy)(pic)3]2+ analogues: catalytic and mechanistic studies.
abstract: A series of mononuclear ruthenium polypyridyl complexes [Ru(Mebimpy)(pic)(3)](PF(6))(2) (2; Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine; pic = 4-picoline), Ru(bimpy)(pic)(3) (3; H(2)bimpy = 2,6-bis(benzimidazol-2-yl)pyridine), trans-[Ru(terpy)(pic)(2)Cl](PF(6)) (4; terpy = 2,2';6',2"-terpyridine), and trans-[Ru(terpy)(pic)(2)(OH(2))](ClO(4))(2) (5) are synthesized and characterized as analogues of the known Ru complex, [Ru(terpy)(pic)(3)](PF(6))(2) (1). The effect of the ligands on electronic and catalytic properties is studied and discussed. The negatively charged ligand, bimpy(2-), has a remarkable influence on the electrochemical events due to its strong electron-donating ability. The performance in light- and Ce(IV)-driven (Ce(IV) = Ce(NH(4))(2)(NO(3))(6)) water oxidation is successfully demonstrated. We propose that ligand exchange between pic and H(2)O occurs to form the real catalyst, a Ru-aqua complex. The synthesis and testing of trans-[Ru(terpy)(pic)(2)(OH(2))](ClO(4))(2) (5) confirmed our proposal. In addition, complex 5 possesses the best catalytic activity among these five complexes.
authors.affiliation: Department of Chemistry, School of Chemical Science and Engineering, Royal Institute of Technology (KTH), Stockholm 10044, Sweden.
authors.forename: Lele
authors.initials: L
authors.lastname: Duan
authors.forename: Yunhua
authors.initials: Y
authors.lastname: Xu
authors.forename: Lianpeng
authors.initials: L
authors.lastname: Tong
authors.forename: Licheng
authors.initials: L
authors.lastname: Sun
mesh_terms: D001562:Benzimidazoles / Q000737:chemistry; D002384:Catalysis; D002412:Cations / Q000737:chemistry; D002563:Cerium / Q000737:chemistry*; D004563:Electrochemistry; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D008027:Light; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010472:Perchlorates / Q000737:chemistry; D010777:Photochemistry / Q000379:methods*; D011725:Pyridines / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry*
chemical_list: D001562:Benzimidazoles; D002412:Cations; D008024:Ligands; D009942:Organometallic Compounds; D010472:Perchlorates; D011725:Pyridines; D014867:Water; D002563:Cerium; D012428:Ruthenium