Mu-eta1:eta1-peroxo-bridged dinuclear peroxotungstate catalytically active for epoxidation of olefins.
The reaction of the dinuclear peroxotungstate, [(n-C4H9)4N]2[{WO(O2)2}2(mu-O)] (II), with H2O2 gives the novel mu-eta1:eta1-peroxo-bridging dinuclear tungsten species, [(n-C4H9)4N]2[{WO(O2)2}2(mu-O2)] (I), which has been characterized by X-ray crystallography, elemental analysis, IR, Raman, UV-vis, and 183W NMR. Only I is active for the epoxidation of cyclic, internal, and terminal olefins, whereas II is inactive for each. The low XSO (XSO=(nucleophilic oxidation)/(total oxidation)) value of I (0.18+/-0.02) in comparison with that of II (0.39+/-0.01) for the stoichiometric oxidation of thianthrene 5-oxide, which is a mechanistic probe for determining the electronic character of an oxidant, reveals that I is more electrophilic than II. On the basis of the kinetic and spectroscopic results, the catalytic epoxidation proceeds by the reaction of I with an olefin to form II and the corresponding epoxide followed by the regeneration of I by the reaction of II with H2O2.
Kamata
Keigo
K
Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Kuzuya
Shinjiro
S
Uehara
Kazuhiro
K
Yamaguchi
Syuhei
S
Mizuno
Noritaka
N
D000475:Alkenes / Q000737:chemistry*; D002384:Catalysis; D003432:Cross-Linking Reagents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004852:Epoxy Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D017973:Tungsten Compounds / Q000737:chemistry*
D000475:Alkenes; D003432:Cross-Linking Reagents; D004852:Epoxy Compounds; D017973:Tungsten Compounds