Ultraviolet photoelectron spectroscopic investigation of electronic structure of some organic thio- and isothio-cyanates and their selenium analogues

Abstract

He(I) photoelectron spectra of CH₃SCN and CH₃SeCN exhibit a series of five ionization bands < 15 eV, the first four being assigned to a sequence of n, π and σ orbitals of the S(Se)CN group on the grounds both of empirical correlations with simpler molecules, and of semi-empirical and ab initio quantum mechanical calculations. Theoretical calculations are reported and discussed also for the isomeric CH₃NCS molecule, already reported in the literature, but re-examined here for comparison. In phenyl-substituted thio- and isothio-cyanates and their selenium analogues, photoelectron spectra are dominated by the presence of strong benzenoid bands, yet some general trends related to structural effects can be recognized.