Intermolecular reactivity trends using the concept of group softness

Density functional theory (DFT) descriptors have been used in the present work to explain "intermolecular" reactivity. Very few parameters have been successful in explaining the concept of intermolecular reactivity sequences until now. It has been shown recently (Roy et al., J. Phys. Chem. 1998, 102, 3746) for the case of carbonyl compounds that local hardness works better than other parameters for predicting intermolecular reactivity trends. In this paper, we show that "group softness" can predict the intermolecular reactivity trends in carbonyl compounds and organic acids correctly. A group is a set of atoms in the molecule that influences the behavior of the most reactive atom in the molecule. Once the group is correctly defined for a series of molecules, group softness is an effective parameter for predicting the most reactive molecule among the given series. The concept of group softness is seen to work efficiently for both types of charge partitioning used and all of the basis sets used for the studies.