Thermochemistry of Organometallic Compounds of Germanium, Tin and Lead

Abstract

Germanium Compounds Tin Compounds Lead Compounds Final Comments Acknowledgements

Dissociation Dynamics and Thermochemistry of Tin Species, (CH3)4Sn and (CH3)6Sn2, by Threshold Photoelectron−Photoion Coincidence Spectroscopy

“…The two starting compounds, tetramethyltin and hexamethylditin, have experimentally determined heats of formation. All values for SnMe 4 listed in recent compilations, such as the NIST Website, Rabinovich et al, Martinho Simoes et al, Cox and Pilcher, and Pilcher, refer back to the1963 heat of combustion work of Davies et al, who reported a liquid-phase heat of formation of −52.3 ± 1.9 kJ·mol −1 . However, when this is corrected for a more recent SnO 2 (s) heat of formation (which was available but not used in previous reviews), the value increases to −49.2 ± 1.9 kJ·mol −1 .…”

“…Our uncertainty of 14.6 kJ mol −1 includes the error in the Me 3 Sn−SnMe 3 heat of formation as well as the error associated with the two Me 3 Sn • radicals. As with the Me 3 Sn−H BDE, Martinho Simoes listed the error in the Sn−Sn bond energy to be 8.4 kJ mol −1 , completely neglecting the ±17 kJ mol −1 uncertainty in the trimethyltin radical. When we include this uncertainty (twice), along with the 8.4 kJ mol −1 , we obtain a total uncertainty of 25 kJ mol −1 .…”

“…Although certainly useful, such reviews highlight the continuing problems in finding reliable thermochemical values. Most of the reviews and compilations of organometallic compounds rely on old experimental values which have not been confirmed by newer methods. As pointed out in the Jover study, high-level calculations for organometallic compounds are difficult to perform, which results in very large discrepancies between calculated and experimental heats of formation, discrepancies that often exceed 30 kJ·mol −1 .…”

Reaction of Germylene with Sulfur Dioxide: Gas-Phase Kinetic and Theoretical Studies

“…The available experimental thermochemical data for germanium compounds are rather sparse. The principal data sources are the NBS and a 1995 article by Martinho-Simoes et al On the other hand, there are a number of theoretical calculations which have sought to calculate the energy surfaces for particular reactions. We have used these in combination with published or estimated enthalpies of formation, to derive values for the enthalpies of formation of H 2 GeO, HGeOH, and GeO 2 which are otherwise not available.…”

“…Collected in Table are the best literature values − we have been able to obtain of Δ H f °(298 K) for the potential end product species of reaction of GeH 2 and SO 2 , as well as the reactants. The available experimental thermochemical data for germanium compounds are rather sparse.…”