Regioselective Arene C–H Borylation with a MOF-Immobilized Iridium Bipyridine Catalyst

Postsynthetic ligand exchange and metalation have been used to immobilize iridium bipyridine precatalysts in MFU-4l with controlled loadings. The resulting materials, 1-Ir-x (x = 0.1–0.5), exhibit high activity for catalytic C–H borylation of arenes, and 1-Ir-0.5 achieves up to 1560 turnover numbers per Ir for toluene substrate. Remarkably, 1-Ir-0.5 exhibits high meta:para product regioselectivity compared to a homogeneous catalyst analogue for arene substrates bearing bulky triisopropylsilyl groups. Density functional theory (DFT) calculations reveal that steric constraints imposed by metal-organic framework (MOF) pore confinement increase the free energy barrier for para C–H activation, biasing product formation toward the meta isomer.