The He(Iα) Photoelectron Spectra of Substituted 1,2-Dithietes

The He(Iα) photoelectron (PE.) spectra of a series of substituted 1,2-dithietes have been recorded and assigned with respect to the orbital sequence derived from an STO-3G model calculation and by correlation with the PE. spectra of related compounds. The results provide additional support for the presence of a closed, four-membered ring moiety in all the 1,2-dithietes investigated. In all cases the two highest occupied molecular orbitals are b2(π)= HOMO, a2(π), with exception of 3,4-bis(trifluoromethyl)-1,2-dithiete where the sequence b2(π), a2(π) or a2(π), b2(π) is uncertain.