How do I find the most reactive sites for electrophilic or nucleophilic attack on my substrate, and what are the electrophilic and nucleophilic atoms on the attacking species?

You can use Jaguar to calculate the f⁻ and f⁺ Fukui functions (using Applications → Jaguar → Fukui Functions). The maximum values of these functions on the molecular surface indicate the most reactive sites. For nucleophilic attack, the largest value of f⁺ indicates the site of attack on the substrate, and the largest value of f⁻ indicates the nucleophile on the attacking species. Conversely, for electrophilic attack, the largest value of f⁻ indicates the site of attack on the substrate, and the largest value of f⁺ indicates the electrophile on the attacking species.

Another way of doing this is to use the atomic Fukui indices (Fukui functions condensed to atoms). The maximum value of f_NN_LUMO for any atom in the substrate indicates the site of nucleophilic attack on the substrate, and for any atom in the attacking species indicates the most electrophilic atom. Likewise, the maximum value of f_NN_HOMO for any atom in the substrate indicates the site of electrophilic attack on the substrate, and for any atom in the attacking species indicates the nucleophilic atom.

More information can be found in Chapter 5 of the Jaguar User Manual.

We do not recommend using atomic charges for the prediction of reactivity.

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