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RESEARCH PRODUCT

Dihydrogen Activation by Antiaromatic Pentaarylboroles

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Facile metal-free splitting of molecular hydrogen (H(2)) is crucial for the utilization of H(2) without the need for toxic transition-metal-based catalysts. Frustrated Lewis pairs (FLPs) are a new class of hydrogen activators wherein interactions with both a Lewis acid and a Lewis base heterolytically disrupt the hydrogen-hydrogen bond. Here we describe the activation of hydrogen exclusively by a boron-based Lewis acid, perfluoropentaphenylborole. This antiaromatic compound reacts extremely rapidly with H(2) in both solution and the solid state to yield boracyclopent-3-ene products resulting from addition of hydrogen atoms to the carbons alpha to boron in the starting borole. The disruption of antiaromaticity upon reaction of the borole with H(2) provides a significant thermodynamic driving force for this new metal-free hydrogen-splitting reaction.