Experimental electronic structures of sulfur dioxide complexes: an electron spectroscopic study

Abstract

He I photoelectron spectra of gas-phase complexes formed by SO{sub 2} with the electron donors trimethylamine, triethylamine, diethyl ether, and diethyl sulfide have been recorded and bands assigned to the different orbitals based on MO calculations. The shift in the ionization energy of the lone pair orbital of the donor in these complexes is shown to vary proportionally with the dissociation energy as well as the magnitude of charge transfer to SO{sub 2}. Electron energy loss spectra of the donor-SO{sub 2} complexes have been recorded to characterize the electronic transitions in the vacuum UV region. Only the amine-SO{sub 2} complex shows a band ascribable to a charge-transfer transition. In order to investigate situations where SO{sub 2} acts as an electron donor, He I spectra of complexes with BF{sub 3} and HCl have been measured. The decrease in the Mulliken population of SO{sub 2} as well as the dissociation energy of these complexes varies parallel to the shift in the lone pair ionization energy of SO{sub 2}.