The ground-state Na+ affinities of a series of substituted acetophenones: a DFT study

A detailed study of Na+ affinities of a series of para-substituted acetophenones and their O-Na+ counterparts was performed using density functional theory [Becke, Lee, Yang and Parr (B3LYP)] method using 6-311G(d,p) basis sets with complete geometry optimisation. The gas-phase O-Na+ complex formation turns out to be an exothermic case and the local stereochemical disposition of Na+ is found to be almost the same in each case. The presence of the para-substituent is seen to cause very little change in the Na+ affinity relative to the unsubstituted acetophenones. Electron-releasing p-substituents increase it by 0.0105 hartree and electron-withdrawing p-substituents decrease it by 0.011 hartree. Computed Na+ affinities are sought to be correlated with a number of computed system parameters such as the net charge on the Na+ and the carbonyl oxygen of the Na+ complexes and the net charge on the carbonyl oxygen of the free bases. The energetics, structural and electronic properties of the complexes indicate that the interaction between the Na+ ion and a carbonyl base is predominantly an ion-dipole attraction and the ion-induced dipole interaction as well rather than a covalent interaction.