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

The electronic and geometrical structure of the ground and low-lying excited states of the SiF _n and SiF_n ^– 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 SiF_n, (n = 0-5) for the fluoride anion are similar.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 44–53, January, 1993.