Part of the potential surface of S4N⊖ has been investigated using the MNDO method. It is found that the cis-trans isomer 1b is more stable by 20-30 kJ/mol than the trans-trans isomer (1 c) and the cis-cis isomer (1 a). The stability of 1 b is traced back to stabilization of the HOMO and to a Coulomb attraction. For S3N2O2 (2) the MNDO calculations favour those isomers (2a and 2b) with two sickle-like arrangements for the same reasons. For S4N3 e (3) only one isomer (3a) is favoured due to the stabilization of the HOMO. The similarity in the transannular interaction present in 1-3 and that in trithiapentalenes and related compounds is pointed out. The PE spectrum of 2 has been reinvestigated. The first five bands can be interpreted by comparison between the measured ionization potentials and the calculated (MNDO) orbital energies.
Zeitschrift für Naturforschung B is an international scientific journal which publishes original papers, microreviews, and letters from all areas of inorganic chemistry, solid state chemistry, coordination chemistry, molecular chemistry, and organic chemistry.