Our efforts during the past eight months were directed towards characterizing synthetic complexes that model the electronic and reactivity properties of the active site of methane monooxygenase (MMO), a metalloenzyme found in methanotrophic bacteria responsible for the biological oxidation of methane to methanol. We have investigated the structural/electronic and reactivity properties of a series of dinuclear model complexes that can function as oxygen atom transfer catalysts. In particular, our studies focused on [Fe[sup 2+][sub 2](H[sub 2]Hbab)[sub 2](N-MeIm)[sub 2]], its DMF solvated form, [Fe[sup 2+][sub 2](H[sub 2]Hbab)[sub 2](DMF)[sub 2](MeIm)], and the mixed valent species [Fe[sup 2+]Fe[sup 3+](H[sub 2]Hbab)[sub 2](DMF)[sub 4]][sup +], (H[sub 4]Hbab = 1,2-bis(2-hydroxybenzamido) benzene). We have also examined [Fe[sup 3+][sub 2](H[sub 2]Hbab)[sub 2](DMF)[sub 4]][sup 2+], [Fe[sup 3+][sub 2](H[sub 2]Hbab)[sub 2](OMe)[sub 2]], and [mu]-oxo-[Fe[sup 3+][sub 2](H[sub 2]Hbab)[sub 2](DMF)[sub 2]], which are unable to act as oxygen atom transfer catalysts.

Our efforts during the past eight months were directed towards characterizing synthetic complexes that model the electronic and reactivity properties of the active site of methane monooxygenase (MMO), a metalloenzyme found in methanotrophic bacteria responsible for the biological oxidation of methane to methanol. We have investigated the structural/electronic and reactivity properties of a series of dinuclear model complexes that can function as oxygen atom transfer catalysts. In particular, our studies focused on [Fe{sup 2+}2(H2Hbab)2(N-MeIm)2], its DMF solvated form, [Fe{sup 2+}2(H2Hbab)2(DMF)2(MeIm)], and the mixed valent species [Fe{sup 2+}Fe{sup 3+}(H2Hbab)2(DMF)4], (H4Hbab = 1,2-bis(2-hydroxybenzamido) benzene). We have also examined [Fe{sup 3+}2(H2Hbab)2(DMF)4]{sup 2+}, [Fe{sup 3+}2(H2Hbab)2(OMe)2], and [mu]-oxo-[Fe{sup 3+}2(H2Hbab)2(DMF){sub 2]}, which are unable to act as oxygen atom transfer catalysts.

The activation of dioxygen by metal ions has both synthetic potential and biological relevance. Dioxygen is the cleanest oxidant for use in emission-free technologies to minimize pollution of the environment. The book gives a survey of those catalyst systems based on metal complexes which have been discovered and studied in the last decade. They activate molecular oxygen and effect the oxidation of various organic compounds under mild conditions. Much of the recent progress is due to a search for biomimetic catalysts that would duplicate the action of metalloenzymes. Mechanistic aspects are emphasized throughout the book. An introductonary chapter reviews the chemistry of transition metal dioxygen complexes, which are usually the active intermediates in the catalytic reactions discussed. Separate chapters are devoted to oxidation of saturated, unsaturated and aromatic hydrocarbons, phenols, catechols, oxo-compounds, phosphorus, sulfur and nitrogen compounds.

This monograph consists of the proceedings of the Fifth International Symposium on the Activation of Dioxygen and Homogeneous Catalytic Oxidation, held in College Station, Texas, March 14-19, 1993. It contains an introductory chapter authored by Professors D. H. R. Barton and D. T. Sawyer, and twenty-nine chapters describing presentations by the plenary lecturers and invited speakers. One of the invited speakers, who could not submit a manuscript for reasons beyond his control, is represented by an abstract of his lecture. Also included are abstracts of forty-seven posters contributed by participants in the symposium. Readers who may wish to know more about the subjects presented in abstract form are invited to communicate directly with the authors of the abstracts. This is the fifth international symposium that has been held on this subject. The first was hosted by the CNRS, May 21-29, 1979, in Bendor, France (on the Island of Bandol). The second meeting was organized as a NATO workshop in Padova, Italy, June 24-27, 1984. This was followed by a meeting in Tsukuba, Japan, July 12-16, 1987. The fourth symposium was held at Balatonfured, Hungary, September 10-14, 1990. The sixth meeting is scheduled to take place in Delft, The Netherlands (late Spring, 1996); the organizer and host will be Professor R. A. Sheldon.

The catalytic activation of dioxygen continues to attract interest both due to its biological importance and synthetic potential. Metalloenzymes play crucial roles in metabolism by living organisms. The modelling of metalloenzymes by biomimetic metal complexes helps the search for useful oxidation catalysts and the understanding of their mechanisms of operation. Dioxygen is also the oxidant of choice in emission-free technologies aimed at minimising pollution of the environment, in line with the green chemistry requirements. This volume is devoted to recent progress in the field of catalytic oxidations using ruthenium, copper, iron, gold, cobalt and other complexes. Products and mechanistic aspects are given special emphasis throughout the book.