Influence of Ligand Architecture on Oxidation Reactions by High‐Valent Nonheme Manganese Oxo Complexes Using Water as a Source of Oxygen

Mononuclear nonheme Mn IV O complexes with two isomers of a bispidine ligand have been synthesized and characterized by various spectroscopies and density functional theory (DFT). The Mn IV O complexes show reactivity in oxidation reactions (hydrogen‐atom abstraction and sulfoxidation). Interestingly, one of the isomers (L 1 ) is significantly more reactive than the other (L 2 ), while in the corresponding Fe IV O based oxidation reactions the L 2 ‐based system was previously found to be more reactive than the L 1 ‐based catalyst. This inversion of reactivities is discussed on the basis of DFT and molecular mechanics (MM) model calculations, which indicate that the order of reactivities are primarily due to a switch of reaction channels (σ versus π) and concomitant steric effects.