20549-65-9Relevant articles and documents
Direct time-resolved study of the gas-phase reactions of germylene with ethyl- and diethylgermane: Absolute rate constants, temperature dependences, and mechanism
Becerra, Rosa,Boganov, Sergey E.,Egorov, Mikhail P.,Krylova, Irina V.,Nefedov, Oleg M.,Walsh, Robin
, p. 1434 - 1440 (2007)
Time-resolved studies of germylene, GeH2, generated by the 193 nm laser flash photolysis of 3,4-dimethyl1 -germacyclopent-3-ene, have been carried out to obtain rate constants for its bimolecular reactions with ethyl- and diethylgermanes in the gas phase. The reactions were studied over the pressure range 1 -100 Torr with SF6 as bath gas and at five temperatures in the range 297-564 K. Only slight pressure dependences were found for GeH2 + EtGeH3 (399, 486, and 564 K). The high pressure rate constants gave the following Arrhenius parameters: for GeH 2 + EtGeH3, log A = -10.75 ±0.08 and Ea = -6.7 ±0.6 kJ mol-1; for GeH2 + Et 2GeH2, log A = -10.68 ±0.11 and Ea = -6.95 ±0.80 kJ mol-1. These are consistent with fast, near collision-controlled, association processes at 298 K. RRKM modeling calculations are, for the most part, consistent with the observed pressure dependence of GeH2 + EtGeH3. The ethyl substituent effects have been extracted from these results and are much larger than the analogous methyl substituent effects in the SiH2 + methylsilane reaction series. This is consistent with a mechanistic model for Ge - H insertion in which the intermediate complex has a sizable secondary barrier to rearrangement.
