Basicity of the carbonyl group. Part 12. Correlations between ionization potentials and Lewis basicities in aromatic carbonyl compounds

Abstract

Linear relationships between ionization potentials of the carbonyl oxygen lone pair and enthalpies of complexation (ΔH°) of the carbonyl group with boron trifluoride are established for three series of para-substituted aromatic carbonyl compounds: benzaldehydes (1), acetophenones (2), and NN-dimethylbenzamides (3). The predictive value of these correlations is explored and the variation of their slopes is discussed in terms of a saturation effect of the direct conjugative interaction between the para-substituents and the variable carbonyl function in the complexed state.