Metallopolymerization as a Strategy to Translate Ligand-Modulated Chemoselectivity to Porous Catalysts


Porous catalysts have garnered substantial interest as potential platforms for group-transfer catalysis due to the ability to site-isolate catalysts and to non-covalently co- localize substrates in proximity to reactive intermediates. In contrast to soluble molecular catalysts, the limited synthetic toolbox available to prepare porous catalysts presents a formidable challenge to controlling the primary coordination sphere of lattice-confined catalysts and thus modulating the electronic structures of reactive catalyst intermediates. Here, we utilize Sonogashira cross-coupling chemistry to prepare a family of porous metallopolymers, in which the primary coordination sphere of Ru2 sites is systematically varied. The newly synthesized materials are characterized by IR, elemental analysis, gas sorption, powder X-ray diffraction, thermogravimetric analysis, X-ray absorption spectroscopy, and diffuse-reflectance UV-vis-NIR spectroscopy. The resulting porous materials are catalysts for nitrene-transfer chemistry and the chemoselectivty for allylic amination of olefin aziridination can be tuned by modulating the primary coordination sphere of the catalyst sites. The demonstration of metallopolymerization as a rational synthetic strategy allows to translate ligand-modulated chemoselectivity to porous catalysts, which represents a new opportunity to tailor the functionality of heterogeneous analogues of molecular complexes.