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-4<i>l</i> with controlled loadings. The resulting materials, <b>1-Ir-</b><i><b>x</b></i> (<i>x</i> = 0.1-0.5), exhibit high activity for catalytic C-H borylation of arenes, and <b>1-Ir-0.5</b> achieves up to 1560 turnover numbers per Ir for toluene substrate. Remarkably, <b>1-Ir-0.5</b> exhibits high <i>meta</i>:<i>para</i> 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 <i>para</i> C-H activation, biasing product formation toward the <i>meta</i> isomer.