Frontispiece: C−H Insertions by Iron Porphyrin Carbene: Basic Mechanism and Origin of Substrate Selectivity

Despite structural similarity and isoelectronic nature between heme carbene and FeIV=O intermediate, our quantum chemical studies for the first time revealed an FeII‐based, concerted, hydride‐transfer mechanism, different from the FeIV‐based stepwise hydrogen‐atom‐transfer mechanism for C−H functionalization by native heme enzymes. A trend of broad range experimental C−H insertion yields and kinetic isotope effects were well reproduced. Origin of substrate selectivity was elucidated. For more information, see the Communication by R. L. Khade and Y. Zhang on page 17654 ff.