title: Theoretical and experimental studies of phenol oxidation by ruthenium complex with N,N,N-tris(benzimidazol-2yl-methyl)amine.
abstract: The ruthenium complex with (N,N,N-tris(benzimidazol-2yl-methyl)amine, L(1)) was prepared, and characterized. Fukui data were used to localize the reactive sites on the ligand. The structural and electronic properties of the complex were analyzed by DFT in different oxidation states in order to evaluate its oxidant properties for phenol oxidation. The results show that the hard Ru(IV) cation bonds preferentially with a hard base (Namine = amine nitrogen, or axial chloride ion), and soft Ru(II) with a soft base (Nbzim = benzimidazole nitrogen or axial triphenyl phosphine). Furthermore, the Jahn-Teller effect causes an elongation of the axial bond in the octahedral structure. The bonding nature and the orbital contribution to the electronic transitions of the complex were studied. The experimental UV-visible bands were interpreted by using TD-DFT studies. The complex oxidizes phenol to benzoquinone in the presence of H2O2 and the intermediate was detected by HPLC and (13)C NMR. A possible mechanism and rate law are proposed for the oxidation. The adduct formation of phenol with [Ru(O)L(1)](2+) or [Ru(OH)L(1)](+) is theoretically analyzed to show that [Ru(OH)L(1)-OPh](+) could produce the phenol radical.
authors.affiliation: Centro Tecnológico, Facultad de Estudios Superiores Aragón (FES-Aragón), Universidad Nacional Autónoma de México (UNAM), México, Estado de México, CP 57130, Mexico.
authors.forename: J Guadalupe
authors.initials: JG
authors.lastname: Hernandez
authors.forename: Antonio Romero
authors.initials: AR
authors.lastname: Silva
authors.forename: Pandiyan
authors.initials: P
authors.lastname: Thangarasu
authors.forename: Rafael Herrera
authors.initials: RH
authors.lastname: Najera
authors.forename: Alfonso Duran
authors.initials: AD
authors.lastname: Moreno
authors.forename: M Teresa Orta
authors.initials: MT
authors.lastname: Ledesma
authors.forename: Julian
authors.initials: J
authors.lastname: Cruz-Borbolla
authors.forename: Narinder
authors.initials: N
authors.lastname: Singh
mesh_terms: D001562:Benzimidazoles / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D056831:Coordination Complexes / Q000737:chemistry*; D004563:Electrochemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010084:Oxidation-Reduction; D019800:Phenol / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D001562:Benzimidazoles; D056831:Coordination Complexes; D019800:Phenol; D012428:Ruthenium; D006861:Hydrogen Peroxide