α-zirconium Phosphonates: Versatile Supports For N-heterocyclic Carbenes

摘要

α-Zirconium phosphonates derivatised with N-heterocyclic carbenes provide a versatile platform for organocatalysis and metal-catalysed transformations, including the ring-opening polymerisation of cyclic esters, and olefin metathesis and hydro-formylations by surface-bound ruthenium, rhodium and iridium complexes.rnThe immobilisation of organo and metal-based catalysts on a variety of solid supports remains crucial for many applications. a-Zirconium phosphonate (ZrP) materials, α-[Zr(O_3PR)_2]_x, are readily accessible hybrid organic-inorganic materials with well-defined structures and are available with high degrees of crystallinity. ZrPs form layer structures that show little variation with the identity of the R group; the lack of surface hydroxy groups can be a significant advantage of ZrPs in the case of early transition metal complexes. The structural homogeneity of these supports facilitates their characterisation by solid-state NMR spectroscopy and X-ray powder diffraction.