COMPUTATIONAL THERMOCHEMISTRY OF MEDIUM-SIZED SILICON HYDRIDES

Standard enthalpies Delta(f)H(298), entropies S-298 and Gibbs function s of formation Delta(f)G(298) for a large number of silicon hydrides c ontaining one to five Si atoms have been calculated. The choice of com pounds includes cyclic and acyclic silanes, silyl radicals, silylenes, disilenes, and cyclic diradicals. The thermodynamic functions were ca lculated using an empirically corrected nb initio scheme. The electron ic energies were obtained with multiconfiguration reference averaged c oupled-pair functional (ACPF) wave functions. Two different basis sets were employed to demonstrate the validity of the correction scheme. T he computed data are compared with experimental and theoretical data f rom other laboratories. Increment rules and substituent effects are pr esented and various reaction enthalpies are tabulated and discussed. T he performance of the correction scheme and potential pitfalls in its general applicability are discussed.