Theoretical investigations into C-H bond activation reaction by nonheme Mn IVO complexes: Multistate reactivity with no oxygen rebound

Abstract

Recently published experimental results on a nonheme synthetic [(Bn-TPEN)Mn IVO] 2+ complex reveal that it is capable of activating strong C-H bonds. However, the final products are shown to contain Mn III instead of the expected Mn II, which should be formed if a rebound mechanism similar to what is assumed for heme Fe IVO was to occur. It was proposed that the substrate radical generated during H-abstraction dissociates from the Mn IIIOH complex and undergoes an additional reaction to a second molecule of Mn IVO, leading to Mn III. Density functional calculations reveal the root cause of why a follow-up rebound to form Mn II and alcohol is not preferred in this system. It is further shown that nonheme Mn IVO has a more complex spin-state manifold during C-H activation reactions compared with Fe IVO, and that spin-state matters in oxidative chemistry of metal-oxo reagents. © 2012 American Chemical Society.