title: Variable pathways for oxygen atom insertion into metal-carbon bonds: the case of Cp*W(O)2(CH2SiMe3).
abstract: Cp*W(O)(2)(CH(2)SiMe(3)) (1) (Cp* = η(5)-pentamethylcyclopentadienyl) reacts with oxygen atom donors (e.g., H(2)O(2), PhIO, IO(4)(-)) in THF/water to produce TMSCH(2)OH (TMS = trimethylsilyl). For the reaction of 1 with IO(4)(-), the proposed pathway for alcohol formation involves coordination of IO(4)(-) to 1 followed by concerted migration of the -CH(2)TMS ligand to the coordinated oxygen of IO(4)(-) with concomitant dissociation of IO(3)(-) to produce Cp*W(O)(2)(OCH(2)SiMe(3)) (3), which undergoes protonolysis to yield free alcohol. In contrast to the reaction with IO(4)(-), the reaction of 1 with H(2)O(2) results in the formation of the η(2)-peroxo complex Cp*W(O)(η(2)-O(2))(CH(2)SiMe(3)) (2). In the presence of acid (HCl) or base (NaOH), complex 2 produces TMSCH(2)OH. The conversion of 2 to TMSCH(2)OH catalyzed by Brønsted acid is proposed to occur through protonation of the η(2)-peroxo ligand, which facilitates the transfer of the -CH(2)TMS ligand to a coordinated oxygen of the η(2)-hydroperoxo ligand. In contrast, the hydroxide promoted conversion of 2 to TMSCH(2)OH is proposed to involve hydroxide coordination, followed by proton transfer from the hydroxide ligand to the peroxide ligand to yield a κ(1)-hydroperoxide intermediate. The migration of the -CH(2)TMS ligand to the coordinated oxygen of the κ(1)-hydroperoxo produces an alkoxide complex, which undergoes protonolysis to yield free alcohol.
authors.affiliation: Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904-4319, United States.
authors.forename: Jiajun
authors.initials: J
authors.lastname: Mei
authors.forename: Kurtis M
authors.initials: KM
authors.lastname: Carsch
authors.forename: Cody R
authors.initials: CR
authors.lastname: Freitag
authors.forename: T Brent
authors.initials: TB
authors.lastname: Gunnoe
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Cundari
mesh_terms: D002244:Carbon / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D011789:Quantum Theory; D014414:Tungsten / Q000737:chemistry*
chemical_list: C581447:Cp*W(O)(2)(CH(2)SiMe(3)); D009942:Organometallic Compounds; D002244:Carbon; D010100:Oxygen; D014414:Tungsten