Using conceptual density functional theory to rationalize regioselectivity: A case study on the nucleophilic ring-opening of activated aziridines

Density functional theory calculations have been performed to rationalize the regiochemistry of the nucleophilic ring opening of activated aziridines. Atomic charges, lowest unoccupied molecular orbitals, Fukui functions and Fukui indices were calculated at the B3LYP/6-311G++(2d,2p) level of theory. Frontier molecular orbital theory, as well as the Fukui function were able to explain the experimentally observed ratios of opening products and a surprising change in regioselectivity upon nitrobenzenesulfonyl activation on the nitrogen. In addition, robustness of atomic charges and Fukui indices to the basis set quality was assessed.