Collect. Czech. Chem. Commun. 2007, 72, 83-99

On the Electronic States of S4+ and S4- Isomers

Hanka Sormovaa, Roberto Linguerria, Pavel Rosmusa,*, Jürgen Fabianb and Najia Komihac

a Laboratoire de Chimie Théorique, Université de Marne la Vallée, F 77454 Champs sur Marne, France
b Institut für Organische Chemie, Technische Universität, D-01062 Dresden, Germany
c Laboratoire de Chimie Théorique, Université Mohamed V-Agdal, Faculté de Sciences, 10000 Rabat, Morocco


For three energetically most stable structures of tetrasulfur, S4, S4+ and S4- (cis-chain, rectangular, and trans-chain forms), equilibrium geometries, harmonic wavenumbers, ionization energies, electron affinities, electronic vertical and adiabatic excitation energies, and electronic transition moments were calculated by ab initio methods. It was found that similarly to the ground state of S4, the S4+ cis-isomer could interconvert, perturbed, however, by vibronic coupling with a very close-lying excited state and large-amplitude vibrations. Moreover, the cis- and rectangular minima are calculated to be energetically degenerated. The ω values in all three species agree reasonably well with existing experimental and theoretical data. The calculated patterns of harmonic modes suggest the existence of very complex low-lying anharmonic polyads in all three species. The calculated ionization energies reported previously are compared with the present more accurate data. Also the electronic transition moments and the energy positions of the electronic states with higher spin multiplicities are given.

Keywords: Sulfur; Ab initio calculations; Geometry optimization; IR spectroscopy; Ionization potential; Electron affinity.

References: 50 live references.