ELECTRONIC-STRUCTURE AND THERMOCHEMISTRY OF SILICON HYDRIDE AND SILICON FLUORIDE ANIONS

An ab initio study of the electronic structure of SiH(n)- and SiF(n)- anions, and the corresponding neutral molecules, has been carried out using perturbation theory. Correlation energy treatments include both MP4 and QCISD methods. The anion thermochemistry is calculated through several isodesmic processes and compared with Pople's G1 and G2 method predictions. Good agreement with experimental electron affinities is found for the SiH(n)- anions. Significant differences (almost-equal-to 10 kcal/mol) are found between theoretical and experimental heats of formation for SiF and SiF2. We find that all SiF(n)- anions (n = 0-3) are stable, with relative stabilities similar to that found for SiH(n)-.