Editorial [Hot topic: Organometallic Chemistry, Coordination Chemistry and Catalysis thematic (Guest Editor: Julio Perez)]

The issue number 15 of Curr. Org. Chem. 2008 (volume 15) consists of four reviews. Their subjects are the application of microwave irradiation to heterofunctionalization of alkenes and alkynes, the oxidative addition of RE-ER (E= S, Se, Te) compounds to transition metal complexes, metallomesogens based on alkane-rich metal complexes, and the dehydrogenative bond-forming catalysis involving phosphines. Daniela M. Ide, Marie P. Eastlund, Casie L. Jupe and Robert A. Stockland Jr.* (University of North Texas, USA) are the authors of the review Microwawe Assisted Heterofunctionalization of Alkenes and Alkynes. Microwave irradiation, compatible with a variety of solvents (and with solvent-free work) and catalysts, can reduce significantly the time and the secondary reactions of chemical reactions, sometimes leading to higher selectivity and functional group tolerance compared with conventional heating. Microwave reactors specifically designed for chemical synthesis, which are already commercially available, allow a precise real-time control of temperature, pressure and microwave power. The reactions covered by this review are the addition of N-H, P-H and O-H bonds, as well as the incorporation of S, Se, Sn and other elements, to alkenes and alkynes, as well as reactions leading to the formation of epoxides and aziridines. Details on the particular experiment, often including the type of reactor, are given in many cases. George C. Fortman, Tamas Kegl*, and Carl D. Hoff (University of Miami, USA, and University of Pannonia, Hungary) have written the paper Kinetic, Thermodynamic, and Mechanistic Aspects of Oxidative Addition Reactions of RE-ER (E = S, Se, Te) and Transition Metal Complexes, which, by means of selected examples, provides an overview of the chemistry of an area of relevance in both industrial and biological realms. The effect of the metal, sometimes within the Cr, Mo, W group, its oxidation state and accompanying ligands (e.g., molybdenum carbonyl complexes vs. tetrathiomolybdate) and the nature of the chalcogen are highlighted. Synthetic work, thermodynamic measurements, and kinetic studies are discussed as well as structural data and theoretical calculations in selected cases. Brenda Porta, Jamal Khamsi, and Juan C. Noveron* (University of Texas at El Paso, USA) wrote the paper Metallomesogens: Supramolecular Design via Alkane-rich Metal Complexes. This review updates the research on metal complexes containing long hydrocarbyl tails, molecules able to generate liquid crystals, organize themselves as micelles or liposomes in aqueous solution, or as Langmuir-Blodgett films on surfaces. The long hydrocarbyl tails, which function is to provide hydrophobic interactions, are usually present at substituents at the backbone of organic ligands. The review is organized by ligand denticity (monodentate, bidentate, etc.) and nature of the donor atoms (N-donors, O-donor, etc.) Rory Waterman (University of Vermont, USA) wrote the article Dehydrogenative Bond-Forming Catalysis Involving Phosphines. The reaction that makes the subject of this paper has been known since just 1995 but, as indicated by the 151 references, attracts much attention, in part due to the central role that phosphines play in coordination chemistry and catalysis. At the same time, this tendency of phosphines to coordinate metal centers is one of the difficulties in the search for catalytic procedures, because that coordination deprives the metal center of the unsaturation needed for catalytic activity. Both early- and late-transition metal complexes catalyze the reaction, and mechanistic studies have begun to provide useful information. The products of the reaction are compounds containing P-P bonds, ranging from diphosphines to cyclic compounds, including unique architectures and compounds that cannot be synthesized by other methods. In addition to these free products, mechanistic investigations highlighted the potential of ligands such as phosphinidenes in catalysis. Some of the catalysts used for the formation of P-P bonds are also effective for heterodehydrocoupling (P-B, P-Ga, P-C, P-Si, P-Ge, P-P (unsymmetric compounds) and P-S. I am sure that, thanks to the great job of the authors and the help of the anonymous reviewers, these reviews will be of interest to the broad readership of Curr. Org. Chem.