for which to collect electronic parameters, we observe that locations closer to the site of change (which would be expected to show the largest variations) may, in fact, produce descriptors less correlated with macroscopic observations. To further test the hypothesis that computed descriptors for aromatic substituents perform better than the ring atoms themselves in describing electronic effects, we sought a more challenging set of experimental data. We selected the oxidative cleavage of olefins with photoexcited nitroarenes, developed by Leonori and co-workers. In this work, the electronic influence of nitroarene substituent(s) on the rate of cycloaddition with a model alkene (adamantylideneadamantane) was explored by an experimental Hammett study using tabulated sigma values. Importantly, several of these substrates have multiple meta-and para-substituents, for which electronic effects were assumed to be additive in the original study (Figure ). The nitroarenes are shown with the logarithm of the experimental reaction rates relative to (unsubstituted) nitrobenzene (log(kX/kH)). Another advantage of using computed electronic descriptors vs. tabulated parameters is that additivity does not need to be assumed -multiply substituted aromatics can instead be computed directly. We applied the same computational protocols discussed above to obtain charge and NMR shift values for the fourteen nitroarenes. We separately obtained parameters at the ipso-C attached to the nitro group and the N atom itself. When compared against experimental relative rates (Figure ),