RPCP pincer ligated iridium complexes (RPCP = κ3-2,6-C6H3(CH2PR2)2) are highly active homogenous catalysts for alkane transfer dehydrogenation. However, the need for a sacrificial olefin hydrogen acceptor in stoichiometric quantities is a limiting factor in the practical application of this methodology. As such, catalytic hydrogen acceptors are of great interest to the improvement of this system. Para-benzoquinones are readily hydrogenated, and the hydroquinone formed upon hydrogenation of a benzoquinone may be oxidized electrochemically to regenerate the parent benzoquinone with release of 2 protons and 2 electrons, making these species ideal candidates for use as catalytic hydrogen acceptors. The stoichiometric reactivity, and catalytic hydrogenation, of para-benzoquinones with iPrPCPIrH4 has been investigated, leading to the discovery of a new class of “barber-chair” pincer complexes. Efforts toward the implementation of para-benzoquinones as electrocatalytic hydrogen acceptors in the PCPIr catalyzed dehydrogenation of alcohols and alkanes will be discussed.

Reactivity of para-benzoquinones with iPrPCPIrH4: In search of new hydrogen acceptors

253rd National Meeting (2017)

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