Cyclometalated phosphine-based pincer complexes: Mechanistic insight in catalysis, coordination, and bond activation

One of the initial steps in the development of therapeutic agents is the identification of lead compounds that bind to the receptor or enzyme target of interest. Many analogs of these lead compounds are then synthesized to define the key recognition elements for maximal activity. In general, many compounds must be evaluated in both the lead identification and optimization steps. Increasing burdens have been placed on these efforts due to the large number of new therapeutic targets that continue to be identified thorough modern molecular biology methods.1 To address this demand, very powerful chemical and biological methods have been developed for the generation of large combinatorial libraries of peptides2 and oligonucleotides3 that are then screened against a receptor or enzyme to identify high-affinity ligands or potent inhibitors, respectively. While these studies have clearly demonstrated the power of library synthesis and screening strategies, peptides and oligonucleotides generally have poor oral activities and rapid in vivo clearance;4 therefore their utility as bioavailable therapeutic agents is often limited. Due to the favorable pharmacokinetic properties of many small organic molecules (<600-700 molecular weight),5 the design, synthesis, and evaluation of libraries of these compounds6 has rapidly become a major frontier in organic chemistry. Lorin A. Thompson was born in Lexington, KY, in 1970. He received the Bachelor of Science degree from the University of North Carolina, Chapel Hill, in 1992 where he worked under the guidance of Joseph Desimone. He is currently pursuing his doctorate in the laboratory of Jonathan Ellman at UC Berkeley where he is the 1994 Glaxo-Wellcome fellow. His research interests include the development of synthetic methodology for organic library construction.

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Synthesis and Applications of Small Molecule Libraries.

http://alpha.chem.umb.edu/chemistry/ch611/documents/C-Htransitionmetalbonds.pdf

Carbonhydrogen-transition metal bonds

C-H oxidation has a long history and an ongoing presence in research at the forefront of chemistry and interrelated fields. As such, numerous highly useful articles and reviews have been written on this subject. Logically, these are generally written from the perspective of the scope and limitations of the reagents employed. This Minireview instead attempts to emphasize chemoselectivity imposed by the nature of the substrate. Consequently, many landmark discoveries in the field of C-H oxidation are not discussed, but hopefully the perspective taken herein will allow C-H oxidation reactions to be more readily incorporated into synthetic planning.

/pdf/if-c-h-bonds-could-talk-selective-c-h-bond-oxidation-3n1lbwrvjm.pdf

If C-H bonds could talk: selective C-H bond oxidation.

Owing to their high uptake capacity at low temperature and excellent reversibility kinetics, metal–organic frameworks have attracted considerable attention as potential solid-state hydrogen storage materials. In the last few years, researchers have also identified several strategies for increasing the affinity of these materials towards hydrogen, among which the binding of H2 to unsaturated metal centers is one of the most promising. Herein, we review the synthetic approaches employed thus far for producing frameworks with exposed metal sites, and summarize the hydrogen uptake capacities and binding energies in these materials. In addition, results from experiments that were used to probe independently the metal–hydrogen interaction in selected materials will be discussed.

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Hydrogen Storage in Microporous Metal-Organic Frameworks with Exposed Metal Sites

Crystal structure of W[C(CMe3)C(Me)C(Me)]Cl3, the archetypal example of a planar delocalized tungstenacyclobutadiene complex

Synthesis and molecular geometry of [(.eta.6-C6H5)As(C6H5)2]Cr(CO)3

Reduction of nitriles by a binuclear tantalum hydride complex. Structural study of [(.eta.5-C5Me4Et)TaCl2](.mu.-.eta.1-N,.eta.2-C,N-NCHMe)(.mu.-Cl)(.mu.-H)[.eta.5-C5Me4Et)TaCl]

X-ray structural study of an alkylidene-carbonyl complex of tungsten(IV): W(:CHCMe3)(CO)(PMe3)2Cl2

The Ta(.mu.-N2)Ta system. 3. Crystal structure of an octahedral tantalum(V) imide complex, mer-Ta(:NPh)(THF)(PEt3)Cl3, and comparisons with related Ta(.mu.-N2)Ta systems

Harvey J. Wasserman

Papers

Crystal structure of W[C(CMe3)C(Me)C(Me)]Cl3, the archetypal example of a planar delocalized tungstenacyclobutadiene complex

Synthesis and molecular geometry of [(.eta.6-C6H5)As(C6H5)2]Cr(CO)3

Reduction of nitriles by a binuclear tantalum hydride complex. Structural study of [(.eta.5-C5Me4Et)TaCl2](.mu.-.eta.1-N,.eta.2-C,N-NCHMe)(.mu.-Cl)(.mu.-H)[.eta.5-C5Me4Et)TaCl]

X-ray structural study of an alkylidene-carbonyl complex of tungsten(IV): W(:CHCMe3)(CO)(PMe3)2Cl2

The Ta(.mu.-N2)Ta system. 3. Crystal structure of an octahedral tantalum(V) imide complex, mer-Ta(:NPh)(THF)(PEt3)Cl3, and comparisons with related Ta(.mu.-N2)Ta systems