Gaussian-3 study of the thermochemistry of the germane and its fluoro chloro derivatives.

The thermochemistry of all fluoro and chloro substituted germane molecules have been theoretically studied. Computed G3//B3LYP standard enthalpies of formation at 298 K obtained from isodesmic reaction schemes were compared with values derived via total atomization energies. Bond dissociation energies and energy barriers for the lowest dissociation pathways were estimated at 0 K. From these data, the most probable dissociation products at 0 K were predicted for the thermal decomposition reactions of the gaseous species. Calculated results are compared with experimental determinations as well as other theoretical data when available. The following isodesmic enthalpies of formation in kcal x mol(-1) were calculated for 10 new germane species simultaneously substituted with fluoro and chloro atoms, for which no previously available computations were found in the literature: GeHFCl2, -125.8; GeCl2F, -104.3; GeHFCl, -67.5; GeF2Cl2, -186.3; GeF3Cl, -242.9; GeH2FCl, -89.7; GeCl3F, -159.6; GeHClF2, -168.0; GeF2Cl, -144.3; GeFCl, -81.1.