La spectroscopie des complexes de transfert de charge peut contribuer à l'interprétation du premier potentiel d'ionisation du donneur (éthylenimine, oxyde d'éthylene, sulfure d'éthylene)

The relationships between the ionization energy (IE) of a donor compound and the position of the UV photoabsorption band of the complex of this donor with iodine as an acceptor are carefully analyzed. Their specificity with respect to (i) the adiabatic and vertical IE and (ii) the nature of the ionized orbital (n or pi) is examined. This analysis allowed us to attempt to determine the nature of the molecular orbital (MO) involved in the ionization process of ethylenimine, ethylene oxide and ethylene sulfide. Very likely the first IE corresponds to the ionization of the non-bonding (n) orbital located on the N and O atoms. Owing to the closeness of the "n" and "pi" IE for sulfides, in the case of ethylene sulfide no conclusion could be drawn.