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Research

Summary

The research conducted in my lab is focused on the reactions between transition metal complexes and simple organic molecules, particularly hydrocarbons. Our work generally involves a mechanism-based approach to the development of catalysts.

     Catalytic functionalization of C-H bonds

The catalytic functionalization of alkanes and other molecules with normally inert C-H bonds is a scientifically challenging problem that presents great opportunities in terms of economics, environmental benefits, and energy self-sufficiency. Catalysts for both the dehydrogenation and the carbonylation of alkanes have been developed in our group; these were among the first efficient organometallic alkane functionalization catalysts.

Pincer catalysts for alkane dehydrogenation

We reported the first efficient solution-phase catalysts for alkane dehydrogenation that require neither the use of photochemical irradiation nor a sacrificial hydrogen acceptor. These “pincer catalysts” have also been found to catalyze reactions as industrially significant as dehydrogenation of n-alkanes, to give the important alpha-olefin products, or dehydrogenation of polymers to allow entry into a diverse manifold of functionalized polymers. Concomitantly, applications in organic synthesis are being investigated.

Alkane Metathesis and other Tandem Systems for Catalytic Hydrocarbon Transformations

Olefins are ubiquitous as intermediates in the petrochemical, commodity chemical, and pharmaceutical industries. Tandem systems that could effect dehydrogenation of alkanes or alkyl groups, followed by a useful secondary reaction of the resulting olefin, offer potentially powerful routes to various products, while avoiding undesirable secondary reactions that can occur in simple alkane dehydrogenation systems. Under the auspices of “CENTC” (see below) and in collaboration with the group of Maurice Brookhart at UNC, we have developed one such system that effects the metathesis of alkanes. A potential application of this system is in the upgrading of Fischer-Tropsch alkane product mixtures to afford greater yields of C9-C19 n-alkanes, ultimately obtained from feedstocks such as coal or biomass. Known as “FT diesel”, this comprises a transportation fuel that burns cleanly and gives ca. 35% greater mileage per ton CO₂ emitted than gasoline.

Hydrocarbylation of olefins

A new target of our research is the “hydrocarbylation” of olefins. Like dehydrogenation, this reaction has an unlimited number of potential applications ranging from natural gas liquefaction and petrochemical conversion to complex organic syntheses.

Computational organometallic catalysis

In addition to experimental approaches, ab initio molecular orbital calculations are conducted in collaboration with Prof. K. Krogh-Jespersen. This work has yielded new perspectives on the most fundamental aspects of organometallic chemistry such as the nature of the metal-CO bond or the process of C-H addition. We now believe that the power of computational chemistry has reached the point where the modification or even the de novo design of catalysts using MO calculations is entirely feasible; efforts in this direction are currently underway.

CENTC  The Center for Enabling New Technologies through Catalysis (CENTC) is the first Center for Chemical Innovation funded by the National Science Foundation. CENTC comprises several catalysis-oriented university and government labs located across the country. Some of the work described above, as well as other projects in our lab, is conducted under the auspices of this center. Much of our research involves collaborations, but CENTC projects will give participating students particular opportunities to interact with other leading catalysis groups.

Awards & Honors