%0 Journal Article
%A Kojima, Takahiko
%A Nakayama, Kazuya
%A Ikemura, Kenichiro
%A Ogura, Takashi
%A Fukuzumi, Shunichi
%D 2011
%T Formation of a Ruthenium(IV)-Oxo Complex by Electron-Transfer Oxidation of a Coordinatively Saturated Ruthenium(II) Complex and Detection of Oxygen-Rebound Intermediates in C–H Bond Oxygenation
%U https://acs.figshare.com/articles/journal_contribution/Formation_of_a_Ruthenium_IV_Oxo_Complex_by_Electron_Transfer_Oxidation_of_a_Coordinatively_Saturated_Ruthenium_II_Complex_and_Detection_of_Oxygen_Rebound_Intermediates_in_C_H_Bond_Oxygenation/2626756
%R 10.1021/ja2037645.s001
%2 https://acs.figshare.com/ndownloader/files/4277444
%K Ru
%K 1 H NMR spectroscopy
%K tridentate fashion
%K uncoordinated pyridine moiety
%K rate constants
%K hydrogen abstraction
%K TPA ligand
%K oxygenated products
%K oraganic substrates
%K bond dissociation energies
%K NMR signals
%K H 2O
%K crystal structure
%K alcohol products
%K 2 proceeds
%K isotope effects
%K DHA
%K room temperature
%K oxygenation reaction
%X A coordinatively saturated ruthenium(II) complex having tetradentate tris(2-pyridylmethyl)amine (TPA) and bidentate 2,2′-bipyridine (bpy), [Ru(TPA)(bpy)]2+ (1), was oxidized by a Ce(IV) ion in H2O to afford a Ru(IV)-oxo complex, [Ru(O)(H+TPA)(bpy)]3+ (2). The crystal structure of the Ru(IV)-oxo complex 2 was determined by X-ray crystallography. In 2, the TPA ligand partially dissociates to be in a facial tridentate fashion and the uncoordinated pyridine moiety is protonated. The spin state of 2, which showed paramagnetically shifted NMR signals in the range of 60 to −20 ppm, was determined to be an intermediate spin (S = 1) by the Evans’ method with 1H NMR spectroscopy in acetone-d6. The reaction of 2 with various oraganic substrates in acetonitrile at room temperature afforded oxidized and oxygenated products and a solvent-bound complex, [Ru(H+TPA)(bpy)(CH3CN)], which is intact in the presence of alcohols. The oxygenation reaction of saturated C–H bonds with 2 proceeds by two-step processes: the hydrogen abstraction with 2, followed by the dissociation of the alcohol products from the oxygen-rebound complexes, Ru(III)-alkoxo complexes, which were successfully detected by ESI-MS spectrometry. The kinetic isotope effects in the first step for the reaction of dihydroanthrathene (DHA) and cumene with 2 were determined to be 49 and 12, respectively. The second-order rate constants of C–H oxygenation in the first step exhibited a linear correlation with bond dissociation energies of the C–H bond cleavage.
%I ACS Publications