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Abstract: Methylthiophenoxyl radical plays an important role as the active form of galactose oxidase (GO), which catalyzes oxidation of a primary alcohol to the corresponding aldehyde. Although many metal(II)‐phenoxyl radical species have been reported, only a few studies have been reported on the properties of methylthiophenoxyl radical‐metal complexes. We have prepared the group 10 metal (Ni, Pd and Pt) complexes of a salen‐type ligand with a methylthio group at para‐position of the two phenolate moieties and characterized them by X‐ray crystal structure analyses and various spectroscopic methods in order to understand the role of the methylthio moiety in phenoxyl radical metal complexes. The corresponding p‐methoxy substituted derivatives have been also characterized for comparison. All the one‐electron oxidized group 10 metal methylthiophenolate complexes have a relatively localized radical site on one of the two phenolate moieties in comparison to the one‐electron oxidized complexes of p‐methoxy derivatives and exhibit different properties dependent on the central metal ions. [ABSTRACT FROM AUTHOR]

A dicopper(II) complex, stabilized by the bis(tpa) ligand 1,2-bis[2-[bis(2-pyridylmethyl)aminomethyl]-6-pyridyl]ethane (6-hpa), [Cu2(μ-OH)(6-hpa)]3+, was synthesized and structurally characterized. This complex catalyzed selective hydroxylation of benzene to phenol using H2O2, thus attaining large turnover numbers (TONs) and high H2O2 efficiency. The TON after 40 hours for the phenol production exceeded 12000 in MeCN at 50 °C under N2, the highest value reported for benzene hydroxylation with H2O2 catalyzed by homogeneous complexes. At 22 % benzene conversion, phenol (95.2 %) and p-benzoquinone (4.8 %) were produced. The mechanism of H2O2 activation and benzene hydroxylation is proposed. [ABSTRACT FROM AUTHOR]

A dicopper(II) complex, stabilized by the bis(tpa) ligand 1,2-bis[2-[bis(2-pyridylmethyl)aminomethyl]-6-pyridyl]ethane (6-hpa), [Cu2(μ-OH)(6-hpa)]3+, was synthesized and structurally characterized. This complex catalyzed selective hydroxylation of benzene to phenol using H2O2, thus attaining large turnover numbers (TONs) and high H2O2 efficiency. The TON after 40 hours for the phenol production exceeded 12000 in MeCN at 50 °C under N2, the highest value reported for benzene hydroxylation with H2O2 catalyzed by homogeneous complexes. At 22 % benzene conversion, phenol (95.2 %) and p-benzoquinone (4.8 %) were produced. The mechanism of H2O2 activation and benzene hydroxylation is proposed. [ABSTRACT FROM AUTHOR]

Proton-coupled electron-transfer oxidation of a RuII−OH2 complex, having an N-heterocyclic carbene ligand, gives a RuIII−O. species, which has an electronically equivalent structure of the RuIV=O species, in an acidic aqueous solution. The RuIII−O. complex was characterized by spectroscopic methods and DFT calculations. The oxidation state of the Ru center was shown to be close to +3; the Ru−O bond showed a lower-energy Raman scattering at 732 cm−1 and the Ru−O bond length was estimated to be 1.77(1) Å. The RuIII−O. complex exhibits high reactivity in substrate oxidation under catalytic conditions; particularly, benzaldehyde and the derivatives are oxidized to the corresponding benzoic acid through C−H abstraction from the formyl group by the RuIII−O. complex bearing a strong radical character as the active species. [ABSTRACT FROM AUTHOR]

Proton-coupled electron-transfer oxidation of a RuII−OH2 complex, having an N-heterocyclic carbene ligand, gives a RuIII−O. species, which has an electronically equivalent structure of the RuIV=O species, in an acidic aqueous solution. The RuIII−O. complex was characterized by spectroscopic methods and DFT calculations. The oxidation state of the Ru center was shown to be close to +3; the Ru−O bond showed a lower-energy Raman scattering at 732 cm−1 and the Ru−O bond length was estimated to be 1.77(1) Å. The RuIII−O. complex exhibits high reactivity in substrate oxidation under catalytic conditions; particularly, benzaldehyde and the derivatives are oxidized to the corresponding benzoic acid through C−H abstraction from the formyl group by the RuIII−O. complex bearing a strong radical character as the active species. [ABSTRACT FROM AUTHOR]

Recently, it was shown that μ-oxo-μ-peroxodiiron(III) is converted to high-spin μ-oxodioxodiiron(IV) through O−O bond scission. Herein, the formation and high reactivity of the anti-dioxo form of high-spin μ-oxodioxodiiron(IV) as the active oxidant are demonstrated on the basis of resonance Raman and electronic-absorption spectral changes, detailed kinetic studies, DFT calculations, activation parameters, kinetic isotope effects (KIE), and catalytic oxidation of alkanes. Decay of μ-oxodioxodiiron(IV) was greatly accelerated on addition of substrate. The reactivity order of substrates is toluene8]toluene is 95 at −30 °C, which the largest in diiron systems reported so far. The present diiron complex efficiently catalyzes the oxidation of various alkanes with H2O2. [ABSTRACT FROM AUTHOR]

Mitochondrial F-ATP synthase produces the majority of ATP for cellular functions requiring free energy. The structural basis for proton motive force-driven rotational catalysis of ATP formation in the holoenzyme remains to be determined. Here, the purification and two-dimensional crystallization of bovine heart mitochondrial F-ATP synthase are reported. Two-dimensional crystals of up to 1 µm in size were grown by dialysis-mediated detergent removal from a mixture of decylmaltoside-solubilized 1,2-dimyristoyl- sn-glycero-3-phosphocholine and F-ATP synthase against a detergent-free buffer. A projection map calculated from an electron micrograph of a negatively stained two-dimensional crystal revealed unit-cell parameters of a = 185.0, b = 170.3 Å, γ = 92.5°. [ABSTRACT FROM AUTHOR]

C−H Activation The formation and high reactivity of the anti‐dioxo form of high‐spin μ‐oxodioxodiiron(IV) as the active oxidant are demonstrated on the basis of resonance Raman and electronic‐absorption spectral changes, detailed kinetic studies, DFT calculations, activation parameters, kinetic isotope effects (KIE), and catalytic oxidation of alkanes. These results provide insight into the high reactivity of the active species Q of soluble methane monooxygenases and the development of efficient alkane oxidation catalysts. For more details, see the Full Paper by M. Kodera et al. on page 5924 ff. [ABSTRACT FROM AUTHOR]