title: Density functional theory study of oxygen-atom insertion into metal-methyl bonds of iron(II), ruthenium(II), and osmium(II) complexes: study of metal-mediated C-O bond formation.
abstract: Metal-mediated C-O bond formation is a key step in hydrocarbon oxygenation catalytic cycles; however, few examples of this reaction have been reported for low-oxidation-state complexes. Oxygen insertion into a metal-carbon bond of Cp*M(CO)(OPy)R (Cp* = η(5)-pentamethylcyclopentadienyl; R = Me, Ph; OPy = pyridine-N-oxide; M = Fe, Ru, Os) was analyzed via density functional theory calculations. Oxygen-atom insertions through a concerted single-step organometallic Baeyer-Villiger pathway and a two-step pathway via a metal-oxo intermediate were studied; calculations predict that the former pathway was lower in energy. The results indicated that functionalization of M-R to M-OR (R = Me, Ph) is plausible using iron(II) complexes. Starting from Cp*Fe(CO)(OPy)Ph, the intermediate Fe-oxo showed oxyl character and, thus, is best considered an Fe(III)O(•-) complex. Oxidation of the π-acid ancillary ligand CO was facile. Substitutions of CO with dimethylamide and NH3 were calculated to lower the activation barrier by ∼1-2 kcal/mol for formation of the Fe(III)O(•-) intermediate, whereas a chloride ligand raised the activation barrier to 26 kcal/mol from 22.9 kcal/mol.
authors.affiliation: Department of Chemistry, Center for Advanced Scientific Computing and Modeling (CASCaM), University of North Texas , Denton, Texas 76203, United States.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Pardue
authors.forename: Jiajun
authors.initials: J
authors.lastname: Mei
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Cundari
authors.forename: T Brent
authors.initials: TB
authors.lastname: Gunnoe