A theoretical investigation of the electronic and geometrical structure of silicon fluorides SiF n and their anions SiF n ?,n=1?6

Abstract

The electronic and geometrical structure of the ground and low-lying excited states of the SiFn and SiFn− series (n = 1-6) are calculated using the density functional method. Energies of fragmentation through different decay channels were evaluated for both series and found to be in good accord with the experimental data and results of nonempirical calculations. The adiabatic electron affinity (EA) of the neutral series is estimated for the first time. The SiF4− anion is shown to be stable toward dissociation though its neutral precursor possesses adiabatic EA close to zero. The SiF5− and SiF6− anions are stable toward dissociation in the gas phase; however, the neutral radical SiF5 is near the stability threshold and SiF6 is unstable as regards dissociation to SiF4+F2. An interesting peculiarity of the silicon fluoride anions is their similar energy of F-detachment, i.e. the affinities of all the neutral SiFn, (n = 0-5) for the fluoride anion are similar.