DISTINGUISHING IONIZATION FROM SULFUR P-TYPE LONE PAIR ORBITALS AND CARBON ?-MOLECULAR ORBITALS BY He I/He II PHOTOELECTRON SPECTROSCOPY

Article abstract of DOI:10.1016/0040-4020(89)80124-3

He I and He II photoelectron spectra of methylthiomethylbenzene (2), 2-(1-methylethylthio)ethylbenzene (3), 1-naphthalenemethanethiol (4), 1,1-dimethylethylthiobenzene (5), benzenethiol (6), and methylthiobenzene (7) are reported.Comparison of the He I and He II band areas for each compound provide a reliable basis for assigning the bands as due to photoionization from a carbon ?-molecular orbital, sulfur p-type lone pair orbital, or mixed orbital.Ionization from a molecular orbital localized on sulfur results in a large decrease in intensity using He II compared with He I as the source relative to ionization from carbon ?-molecular orbitals.Mixed orbitals with both sulfur and carbon character also give rise to diminished intensities in the He II versus He I spectra relative to pure carbon orbitals, but proportionately less decrease than pure sulfur orbitals.