Conversion of Molecular Oxygen into a Hydroperoxo Species by Ring-Opening Protonation of a Cyclic η2-Peroxo Intermediate: Characterization of the η2-Peroxo and Hydroperoxo Complexes

A transition metal–hydroperoxo species is formed by the oxygenation of a low-valent rhodium precursor followed by a protonation of the resulting η²-O₂ ligand; the latter process is assisted by an intramolecular hydrogen-bonding interaction (see scheme). This process is the first structural evidence for an effective method for the activation of molecular oxygen as postulated for the cytochrome P-450 system.     

Synthesis of a telechelic polypropylene with a vanadium-based living polymerization catalyst

The V(acac)₃ (acac = acetylacetonato)/AlEt₂Cl catalyst is known to promote the living polymerization of propylene at low temperature. In the present study, the catalyst was modified by contacting with α,ω-unconjugated diene compounds, and the resulting catalyst was applied to propylene polymerization. The polymer produced shows a bimodal molar mass distribution, where the molecular weight of the higher molecular weight portion is twice that of the lower molecular weight portion. By using the CO quenching technique, it was found that the polymer with the higher molecular weight has a telechelic structure.     

Oxygenative Cleavage of Chlorocatechols with Molecular Oxygen Catalyzed by Non-Heme Iron(III) Complexes and Its Relevance to Chlorocatechol Dioxygenases

The degradation of halogenated arenes , which are considered as hazardous compounds from a toxicological and environmental point of view, can be effected by non-heme iron enzymes such as chlorocatechol dioxygenases. In principle, this process of biological oxygenation mimics the reaction of the iron complex shown below [Eq. (a); Py=2-pyridyl].     

Poly(phenylhydrosilane): Base-developable polysilane resist

Poly(phenylhydrosilane) becomes soluble in a 2.38% tetramethylammoniumhydroxide aqueous solution after exposure to UV light. This is the first report that the polysilanes not bearing acidic groups can be developed with dilute basic aqueous solutions. Addition of 3,3′,4,4′-tetra(t-butylperoxycarbonyl)benzophenone increases the resist sensitivity. The reaction mechanism is as follows: PS1 photodecomposes to form silyl compounds having SiOH groups, which become soluble in an aqueous base solution, because these silane compounds bearing SiOHs are acidic. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2355–2364, 1997     

New crystalline polymers: poly(2,5‐dialkyl‐1,4‐phenylene oxide)s

New heat‐reversibly crystalline poly‐(alkylated phenylene oxide)s are described. the oxidative polymerization of 2,5‐dimethylphenol catalyzed by (1,4,7‐triisopropyl‐1,4,7‐triazacyclononane) copper dichloride produced poly(2,5‐dimethyl‐1,4‐phenylene oxide), which showed heat‐reversible crystallinity with a high melting point at ca. 300°C, although the isomeric polymer, poly(2,6‐dimethyl‐1,4‐phenylene oxide), never recrystallizes once melted. The polymerization of 2,5‐diethylphenol and 2,5‐dipropylphenol gave the polymers consisting of 1,4‐phenylene oxide units; the latter polymer possessed heat‐reversible crystallinity, however, the former one did not.