Asymmetric Hydrogen Atom Transfer Reactions. Several recent advances have been made in the development of methods for enantioselective mHAT olefin hydrofunctionalization, each of which uses cobalt catalysts with chiral ligands. These examples include both intramolecular and intermolecular reactions with alcohols, 13 heteroarenes, and various nitrogen sources. To the best of our knowledge, however, no studies have reported any enantioselective mHAT olefin functionalization or hydrogenation that uses an Fe-based catalyst. This difference between metals may be due to the higher bond dissociation free energy (BDFE) of the Co-C bond in the cobalt(IV)-alkyl intermediate (calcd. 22 kcal/mol 16 ) relative to the very weak BDFE for the putative Fe-C bond in the iron(III)alkyl intermediate (calcd. 1.5 kcal/mol 17 ). Indeed, organocobalt species arising from cobalt mHAT can be isolated, while analogous alkyl intermediates from iron mHAT have yet to be characterized experimentally. The relative stability of [Co IV ]-alkyl intermediates in particular enables them to undergo nucleophilic attack via an SN2 mechanism and to provide enantioinduction through use of a chiral ligand. In contrast, the Fe-C bond is too weak to proceed through a similar SN2 mechanism, homolyzing before any opportunity arises for chiral information to be transmitted by a supporting ligand.