Abstract

Different theoretical descriptors of nucleophilicity have been proposed in the literature, the most simple among them is perhaps the recently proposed nucleophilicity N index which is simply the energy subtraction of the energy of the highest occupied molecular orbital (HOMO) between the evaluated system and a reference molecule. Other indexes are based on the electrophilicity index and electrodonating power indexes. However there are not a total agreement between these indexes and the N index in describe reactivity trends. In this work, we performed a comparative analysis between these indexes and decomposed them in their components. The principal difference of these indexes is the inclusion of the hardness in some of them. Therefore, the apparent limitation in describe reactivity against electrophiles of these indexes is due to the nature of the evaluated systems used to evaluate their performance, i.e. if the reactivity is evaluated into the context of the soft-soft interaction the best descriptor should be the HOMO energy, but what happens when hard interaction is considered?. Our preliminary results suggest that in these cases the inclusion of hardness into the model is necessary to describe correctly the reactivity.