Event

New Title “Bimetallic Catalysis in Biology & Synthesis”

Catalysis research in organometallic systems has traditionally focused on single-site mechanisms, often involving oxidative addition and reductive elimination reactions as key steps. Because of the multielectron nature of these two reactions, only a small subset of chemical elements (mostly precious metals like Rh, Ir, Pd, Pt) that have favorable multielectron redox properties typically can participate. In principle, pursuing related mechanisms that incorporate bimetallic oxidative addition and bimetallic reductive elimination or some other cooperative behavior would provide access to a complementary chemical reactivity space while removing the requirement for an individual metal site to access multielectron redox transformations catalytically. Not only would such catalytic strategies widen the range of viable catalytic elements (including base metals like Mn, Fe, Cu, Zn), but also they are likely to give rise to new modes of reactivity and/or selectivity. In this presentation, our group’s efforts at studying bimetallic catalysts of the formulation (NHC)Cu-[MCO] (NHC = N-heterocyclic carbene, [MCO]- = metal carbonyl anion) will be presented. Through tuning the nature of the Cu/M pairing in the catalyst, we have successfully achieved catalytic C-B coupling, C-C coupling, CO2 deoxygenation, and hydrogenation reactions, all of which require bimetallic cooperativity to achieve turnover. The hypothetical mechanisms and their roles in unveiling novel reactivity and selectivity patterns will be discussed. Collectively, the growing list of catalytic transformations available to this single bimetallic catalyst design mimics the behavior of familiar single-site precious metal systems and provides support to the bimetallic hypothesis as a promising paradigm in homogeneous catalysis.

Inquiries please contact Rosa M. Vargas rvargas@sas.upenn.edu