The Li+ affinities of a series of substituted acetophenones in their low-lying excited triplet state: A DFT study

Abstract A detailed study of Li + affinities of a series of para–substituted acetophenones and their O–Li + counterparts was performed using density functional theory (Becke, Lee, yang and parr [B3LYP]) method using 6-311G(d,p) basis sets with complete geometry optimization in the relevant excited state. The gas phase O–Li + complex formation turns out to be exothermic case and the local stereochemical disposition of the Li + is found to be almost the same in each case. The presence of para-substituent is seen to cause very little change of the Li + affinity relative to the unsubstituted acetophenones. Electron releasing p-substituents increase it by 0.028 hartree and electron withdrawing p-substituents decrease it by 0.006 hartree. Computed Li + affinities are sought to be correlated with a number of computed system parameters such as the net charge on the Li + and the carbonyl oxygen of the Li + complexes and the net charge on the carbonyl oxygen of the free bases and also the computed hardness of the free bases. The Li + ion-induced shifts are in general red shifts for the low-lying excited triplet state. The energetics, structural and electronic properties of the complexes indicate that in the lowest excited triplet state the interaction between the Li + ion and a carbonyl base is predominantly an ion–dipole attraction and the ion-induced dipole interaction as well rather than a covalent interaction.