Hierarchical Porous Organometallic Polymers Fabricated by Direct Knitting: Recyclable Single-Site Catalysts with Enhanced Activity.

Porous organometallic polymers (POMPs) with hierarchical pore structures, high specific surface areas, and atomically dispersed metal (Ir, Pd, Ru) centers are successfully fabricated by a facile one-pot method through direct knitting of diverse N-heterocyclic carbene metal (NHC-M) complexes. These polymers can function as recyclable solid single-site catalysts and exhibit excellent catalytic activity and selectivity in both dehydrogenation and hydrogenation reactions even at ppm-level catalyst loadings. Remarkably, a record turnover number (TON) of 1.01 × 106 is achieved in the hydrogenation of levulinic acid to γ-valerolactone, which is 750 times higher than that attained with corresponding bis-NHC-Ir complex.