Stabilizing unstable species through single-site isolation: a catalytically active TaV trialkyl in a porous organic polymer

Abstract

A catechol-functionalized porous organic polymer (POP) has been successfully metallated with a Ta^V trialkyl and remains thermally and structurally robust. The resulting POP-supported (catecholato)Ta^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^V trialkyl site and its products in reactions with Brønsted 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.