Richard Bartetzko

Electronic structure of 1,5-dithia-2,4,6,8-tetraazocine. Model calculations and spectroscopic investigations

Les calculs de modele (ab initio et MNDO) de la dithia-1,5 tetrazocine-2,4,6,8 montrent que le systeme 10-π riche en electrons prefere une structure plane monocyclique. Les substituants donneurs peuvent induire une distorsion pseudo Jahn-Teller conduisant a un systeme 8-π bicyclique. Les resultats de ces calculs sont etayes par des resultats experimentaux (spectres de photoelectrons, visible, UV etc.)

The Structure of Thiodithiazyl Derivatives. An Example of an Electron-Rich-Four-Center-Bond

Experimental and computational evidence indicates that the five-membered ring system S3N2+ has an 2A2 ground state. Different possibilities for the stabilization of S3N2+ are discussed on the basis of MO arguments and calculations using semiempirical and ab initio (STO 3G) methods. The theory allows the rationalization of the structures of S3N2Cl2, S3N2X and [S6N4]2+. The bonding between the two S3N2+ moieties in [S6N4]2+ is described as an electron rich six electron four center bond.

The Structure of the Cyclopentathiazenium Cation (S5N5 +) - a MNDO Investigation

Abstract The total energies, heats of formation (⊿Hf), bond lengths and bond angles of four isomers of S5N5+ (1) have been calculated using the MNDO method. The heart shaped and azulene like structures 1 e and 1 f have been found to be the most stable isomers with about equal energies.

The Structures of S4N⊖, S3N2O2 and S4N3⊖

Abstract 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.