title: Dioxygen Activation by Non-Adiabatic Oxidative Addition to a Single Metal Center.
abstract: A chromium(I) dinitrogen complex reacts rapidly with O2 to form the mononuclear dioxo complex [Tp(tBu,Me)Cr(V)(O)2] (Tp(tBu,Me) = hydrotris(3-tert-butyl-5-methylpyrazolyl)borate), whereas the analogous reaction with sulfur stops at the persulfido complex [Tp(tBu,Me)Cr(III)(S2)]. The transformation of the putative peroxo intermediate [Tp(tBu,Me)Cr(III)(O2)] (S = 3/2) into [Tp(tBu,Me)Cr(V)(O)2] (S = 1/2) is spin-forbidden. The minimum-energy crossing point for the two potential energy surfaces has been identified. Although the dinuclear complex [(Tp(tBu,Me)Cr)2(μ-O)2] exists, mechanistic experiments suggest that O2 activation occurs on a single metal center, by an oxidative addition on the quartet surface followed by crossover to the doublet surface.
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716 (USA).
authors.forename: Eser S
authors.initials: ES
authors.lastname: Akturk
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716 (USA).
authors.forename: Glenn P A
authors.initials: GP
authors.lastname: Yap
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716 (USA). theopold@udel.edu.
authors.forename: Klaus H
authors.initials: KH
authors.lastname: Theopold
mesh_terms: D002857:Chromium / Q000737:chemistry*; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D009942:Organometallic Compounds; D002857:Chromium; D010100:Oxygen
keywords: ab initio calculations; chromium; dioxygen activation; spin-forbidden reactions; sulfur