A functional model for pMMO (particulate methane monooxygenase): Hydroxylation of alkanes with H2O2 catalyzed by beta-diketiminatocopper(II) complexes.
The reaction of copper(II) complexes supported by a series of beta-diketiminate ligands ((R1,R2)L, [(Dipp)N-C(R(2))-C(R(1))-C(R(2))-N(Dipp)](-), Dipp=2,6-diisopropylphenyl; see ) and H(2)O(2) has been examined spectroscopically at a low temperature. The beta-diketiminatocopper(II) complexes with R(2)=H (no substituent on the beta-carbon) provided a copper-oxygen intermediate that exhibited the same spectroscopic features as those of the bis(mu-oxo)dicopper(III) complex generated by the reaction of corresponding beta-diketiminatocopper(I) complex and O(2). On the other hand, the beta-diketiminatocopper(II) complexes with methyl substituent on the beta-carbon (R(2)=Me) did not produce such an intermediate in the same reaction. The beta-diketiminatocopper(II) complexes carrying an electron-withdrawing substituent on the alpha-carbon (R(1)=NO(2) or CN) but no beta-substituent (R(2)=H) exhibited a high catalytic activity in the oxygenation reaction of alkanes with H(2)O(2). Mechanism of the catalytic oxygenation reaction as well as the substituent effects of the ligands on the copper(II)-H(2)O(2) reactivity is discussed.
Departments of Chemistry and Materials Science, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
Chizu
C
Shimokawa
Junji
J
Teraoka
Yoshimitsu
Y
Tachi
Shinobu
S
Itoh
D000473:Alkanes / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006900:Hydroxylation; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013059:Spectrum Analysis, Raman
D000473:Alkanes; D003300:Copper; D006861:Hydrogen Peroxide; D010105:Oxygenases; C021555:methane monooxygenase