Electron charge redistribution upon hydride addition to carbonylic compounds

The variation of atomic charges upon hydride addition to carbonylic compounds comprising: ketones, aldehydes, carboxylic acids, esters, and amides were studied using two different atomic partitionings: the QTAIM and the Hirshfeld scheme. The absolute charges for the electronegative atoms and those bonded to them obtained with both schemes are significantly different. Nevertheless, the variations in atomic charges observed upon the hydride addition are quite similar and contradict the trends expected according to the resonance model. Thus, most of the negative charge of the anion resides on the hydrogen atoms and not on the carbonyl oxygen as is generally accepted.