Bifunctional catalysis with boratranes

Abstract

Transition metal catalyzed bond forming reactions often involve formal two-electron redox steps (e.g. Oxidative addn. and reductive elimination). Noble metal catalysts are commonly used in these reactions due, in part, to their propensity to facilitate these multi-electron processes. By contrast, first row metal complexes often engage in 1-electron reaction steps. But there is growing interest and substantial promise in developing catalysts for bond forming/cleavage reactions based on earth abundant mid-to-late first-row transition metals. First row metallaboratranes are appealing as catalysts because of the boron center's ability to stabilize low valent metals and serve as a hydride acceptor. As such, metallaboratranes can mediate 2-electron reaction steps. Akin to frustrated Lewis pairs (FLPs) that employ main group donor and acceptor partners, our group has recently reported a demonstrative example wherein nickel boratranes facilitate H_2 activation and catalytic hydrogenations. We have since been exploring E-H bond addn. across M-B bonds more generally, for example where M = Fe, Co, and Ni. In this talk I will summarize what we have learned to date, and where we think ripe opportunities exist for productive bifunctional catalysis.

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