Stabilizing unstable species through single-site isolation: a catalytically active Ta super(V) trialkyl in a porous organic polymer

A catechol-functionalized porous organic polymer (POP) has been successfully metallated with a Ta super(V) trialkyl and remains thermally and structurally robust. The resulting POP-supported (catecholato)Ta super(V) trialkyl sites remain accessible to small molecules and can undergo reactions to yield stable, monomeric complexes that are quite different from those observed with the homogeneous analogues. Using a combination of reactivity studies, high-resolution solid-state NMR spectroscopy, and X-ray absorption spectroscopy (XAS), we are able to precisely determine the functionality and coordination environment of the active (catecholato)Ta super(V) trialkyl site and its products in reactions with Broensted acids. Additionally, the Ta-metallated POP was found to have enhanced catalytic activity in the hydrogenation of cyclohexene and toluene relative to a homogeneous analogue.