Low valent bisphosphinoborane transition metal compounds: Unusual coordination chemistry and E-​H bond activation

Recently there has been great interest in the use of transition metal compds. supported by a redox active ligand which are able to serve as bifunctional catalysts for two electron processes. We have previously shown that iron aminoimide compds. bearing bisphosphinoborane ligands activate of Si-H and H-H bonds to generate hydrazido and amide species. We have also reported activation of H-H and Si-H bonds in the context of catalytic hydrogenation of olefins and hydrosilylation of aldehydes by related low valent nickel compds. Computational studies of the Ni system have alluded to the importance of the M-B interaction in the activation of E-H bonds. The M-B unit in these compds. can be thought of as a transition metal based frustrated Lewis pair with an electron rich metal center acting as the base with the nearby Lewis acidic borane acting as a hydride acceptor. Efforts to expand this chem. to other low valent metal centers supported by a similar ligand scaffold and the resultant coordination chem., E-H bond activation chem. and catalytic activity towards some small mols. will be discussed