The impact of the electronic properties of the catalyst on the enantioselectivity in the currently studied reaction deserves discussion. Previous studies on asymmetric olefin epoxidation demonstrated that the systematic increase in the electron density of the Fe and Mn complexes, led to a notable improvement in enantioselectivity: the less electrophilic the metal-oxo species, the closer the olefin is to the chiral pocket of the catalyst in the transition state (TS) consistent with the Hammond postulate. Moreover, the catalytic activity was also improved, an aspect that was interpreted as a result of a more effective push effect that assists H2O2 activation. The electronic dependence observed in our system (Figure ) contrasts with those observed in oxygen atom transfer reactions. To understand this phenomenon and to complement the interpretation of MLR modelling, we undertook computational studies of the TS structures for the [Mn V O(OAc)(pdp)] 2+ and [Mn V O(OAc)( NMe2 pdp)] 2+ species undergoing HAT from the axial C3-H bond of the model substrate S1, the enantiodetermining step. Previous studies performed in fluorinated alcohol solvents demonstrated that hydroxylation at this bond dominates over that at the equatorial C3-H, and that the former is associated to a significantly higher enantioselectivity in the hydroxylated product. Therefore, we proceeded under the assumption that for all catalysts the generation of the chiral axial Analogously, TS structures computed for the reaction with [Mn V O(OAc)( NMe2 pdp)] 2+ resemble those obtained with [Mn V O(OAc)(pdp)] 2+ . The difference in activation free energy between these systems is 0.34 kcal/mol, close to that measured in the catalytic assays (G ‡ exp = 0.24 kcal/mol) and predicted by the MLR model (G ‡ MLR = 0.23 kcal/mol). Interestingly, compared to the corresponding reaction with [Mn V O(OAc)(pdp)] 2+ , the length of the C-H bond that is cleaved remains virtually unaffected (1.13 Å). Additionally, the O-H bond that is formed is shortened likely due to the lower reactivity of the [Mn V O(OAc)( NMe2 pdp)] 2+ species in executing HAT.