The Electronic Structure of 1,3-Dithiole-2-thione and Its Selenium Analogues. Photoelectron Spectra and Polarized Electronic Absorption Spectra

Abstract

The He I photoelectron (PE) spectra of 1,3-dithiole-2-thione (1) and its selenium analogues 2-6 have been investigated. The first five bands in the PE spectrum of 1 could be assigned to transitions corresponding to removal of electrons from 5b2, 3b1, 1 la2, 2b1, 4b2, and 7a1 orbitals. This assignment is based on a comparison of the PE spectra of 1-6 and on molecular orbital calculations using a ZDO model, and the PPP, EH, and the MINDO/3 methods. The UV polarized absorption spectra of 1,3,4, and 6 have been measured by means of the stretched film technique. The measurements were performed in polyethylene sheets at 77 K. Several bands could be assigned to π* ← iπ and π* ← n transitions by comparison with model calculations. The results from both types of measurement could be understood in terms of a simple MO diagram. © 1977, American Chemical Society. All rights reserved.