A PCP Pincer Ligand for Coordination Polymers with Versatile Chemical Reactivity: Selective Activation of CO₂ Gas over CO Gas in the Solid State

Abstract

At etra(carboxylated) PCP pincer ligand has been synthesized as ab uilding blockf or porous coordination polymers (PCPs). The air-a nd moisture-stable PCP metalloligands are rigid tetratopic linkers that are geometrically akin to ligands used in the synthesis of robust metal-organic frameworks (MOFs). Here,t he design principle is demonstrated by cyclometalation with Pd II Cl and subsequent use of the metalloligand to prepare ac rystalline 3D MOF by direct reaction with Co II ions and structural resolution by single crystal X-ray diffraction. The Pd À Cl groups inside the pores are accessible to post-synthetic modifications that facilitate chemical reactions previously unobserved in MOFs:aPd À CH 3 activated material undergoes rapid insertion of CO 2 gas to give PdÀOC(O)CH 3 at 1atm and 298 K. However,s ince the material is highly selective for the adsorption of CO 2 over CO, aPd À N 3 modified version resists CO insertion under the same conditions.