Among electronic descriptors, NMRC1 max was found to be an appropriate molecular descriptor for predicting the efficiency of the acids. The negative value of the coefficient indicates that the probability that the P1 yield will experience erosion increases as the electron-withdrawing character of the acid increases. For instance, the probability that the simple acetic acid provides a P1 yield lower than 20% is severely reduced by 90% when incorporating strong electron-deficient groups such as CF3 (A2) and CN (A7) at the -carbon. We reasoned that electron-rich acids would better coordinate to the Mn center facilitating the heterolytic cleavage of H2O2, while stabilizing the electrophilic [Mn V O(OCOR)(N4L)] 2+ species. The negative coefficient of %Vbur min suggests that bulky carboxylic acid co-ligands are deleterious to the reaction. For instance, substituting acetic acid (A1, for which %Vbur min = 6.6) for cyclohexanecarboxylic acid (A26,%Vbur min =14.6), the likelihood that the system provides a P1 yield higher than 20% is reduced by 42%. Likewise, using bulky carboxylic acids such as A23 (%Vbur min = 16.8) and A25 (%Vbur min = 17.4), significantly increases the probability (by 80-84%) of lowering the yield of P1 below 20%. It is reasonable to consider that the increase in co-ligand size significantly reduces catalyst pocket free space, limiting accessibility to the manganese oxo unit for the incoming substrate. However, it is important to mention that the lack of P1 formation when using branched carboxylic acids may be also explained in terms of competition between the intermolecular amide substrate oxidation and intramolecular directed oxidation of carboxylic acids. For instance, 4methylpentanoic acid (A10) bearing a tertiary -C-H bond, undergoes intramolecular -lactonization generating 5,5-dimethyl-dihydro-furan-2-one, and this completely overrides the intermolecular oxidation of S1. Although such analysis provides evidence that the size of the acid clearly impacts reaction output, as noted by the model equation, the interplay of both terms is not inconsequential.