Electronic interaction in heterosubstituted acetones studied by means of ultraviolet photoelectron and electron transmission spectroscopy

The HeI and HeII photoelectron and the electron transmission spectra of some heterosubstituted acetones CH3COCH2X [X = F, Cl, Br, I, SC2H5, OCH3, N(CH3)2, and C2H5] have been recorded. They have been interpreted with the help of ab initio computations using the pseudopotential method of Barthelat et al. The energy trend of the MOs mainly localised at the carbonyl group (πCO, πCO*, and nO) is discussed in terms of the various electronic interactions with the group orbitals of the X substituent. Finally, the nO–πCO* energy gap is related to the variation of the energy of the πCO*â†�nO u.v. transition.