Moasser, Bahram - Georgetown University

个人简介

A.B. 1987, Cornell University M.S. 1990, University of Wisconsin Ph.D. 1995, University of Minnesota Research Scientist, 1995-2006, General Electric Global Research Center, Niskayuna, NY

研究领域

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We are a growing research group that is broadly interested in synthetic and mechanistic inorganic/organic chemistry. Research in our group is highly multi-disciplinary. Our interests span organometallic chemistry, homogeneous catalysis, green chemistry and new synthetic methods. We are focused on the projects outlined below; however, we are sometimes seduced by interesting and unanticipated outcomes that draw us into unplanned research areas. New Synthetic Methods We believe that understanding reaction mechanisms on a fundamental level will result in the development of new synthetic methodology and provide practical solutions to unmet needs in the area of inorganic and organic synthesis. A specific example of the type of reaction we are interested in is what Noyori has termed “metal-ligand bifunctional” hydrogenation of unsaturated organic substrates, such as, aldehydes, ketones, or imines. Noyori and Casey have both described example of this kind of reactivity involving the concerted transfer of proton, from a proximal (protic) ligand NH or OH, and hydride (Ru-H) to carbonyls. Our focus is to understand the scope and limitations of ligand non-covalent interactions in the transition state for metal-ligand hydrogenation reactions. Currently, we are studying ligand modifications on the classical eta(6)arene-ruthenium piano-stool motif to better understand ligand effects on metal-ligand hydrogenation reactions. The groundbreaking work by Noyori and Casey has inspired us to take a more holistic view of such organometallic complexes and to regard the metal-ligand ensemble with an enzyme-like perspective, with all parts of the molecule contributing to the critical elements of structure and reactivity. Therefore, we are exploring related reactions that may involve the cooperative participation of metal and ligand resulting in activation of a substrate. For example, we are designing catalysts that would be able to hydrogenate substrates, such as amides, that have thus far been unreactive to this type of reduction. Green Chemistry The study of reaction mechanisms drives the design of more efficient and selective catalysts. The environmental benefits of increasing catalytic efficiency are in lowering process power consumption; the benefits of higher selectivity are in reducing unwanted waste byproducts. Moreover, the ability to perform reactions under conditions that permit the capture and reuse of the catalyst phase eliminates energy-intensive separations and streamlines processes. Many times the adaptation of traditional reactions to green versions is more or less straightforward. Several commercially viable and greener chemical processes have successfully translated well-understood organic phase reactivity of transition metal catalysts into the aqueous or aqueous biphasic medium by ligand modifications. Other approaches rely on rethinking a chemical transformation on the molecular level and designing a completely new way of accomplishing the same synthetic transformation. In keeping with the latter approach we are interested in incorporating emerging ideas in hydrogen activation to design less wasteful catalytic methods that would replace traditional atom-inefficient synthetic approaches.