A THEORETICAL INVESTIGATION ON THE MOLECULAR AND ELECTRONIC-STRUCTURE OF THE SF(N) COMPOUNDS N = 1-5 AND THEIR SINGLY CHARGED NEGATIVE-IONS

The electronic and molecular structures of binary sulphur fluorides SFn (n = 1,5) as well as their singly charged anions have been studied by a computational method based on density functional theory. Ground state conformations as well as geometries for all excited states below 4 eV are presented for SFn and SFn-. It was found that all anions have more than one state which is stable with respect to ligand dissociation and electron detachment. Calculations have been carried out on the first S-F ligand dissociation energy D(SFn-1 - F), as well as the adiabatic electron affinity EA(ad). The D(SFn-1 - F) and EA(ad) values made it possible to estimate decomposition energies for SFn- with respect to different fragmentation channels. The topmost dissociation channel of SFn- Corresponds to the SFn-1 + F- decay, followed by the SFn-2 + F2- dissociation. The electronic structure of binary sulphur fluorides is largely determined by the four 3s(s) and 3p(s) sulphur orbitals. The sulphur based orbitals are either nonbonding or antibonding with respect to the fluorine atoms and make up the highest occupied and lowest unoccupied orbitals in all systems. The shapes of the sulphur fluorides and their anions have been rationalized in terms of these four orbitals.