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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Direct time-resolved study of the gas-phase reactions of germylene with ethyl- and diethylgermane: Absolute rate constants, temperature dependences, and mechanism
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Direct time-resolved study of the gas-phase reactions of germylene with ethyl- and diethylgermane: Absolute rate constants, temperature dependences, and mechanism

机译：杀菌剂与乙基和二乙基锗烷的气相反应的直接时间分辨研究：绝对速率常数，温度依赖性和机理

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摘要

Time-resolved studies of germylene, GeH2, generated by the 193 nm laser flash photolysis of 3,4-dimethyl-1-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 GeH2 + EtGeH3, log A = -10.75 +/- 0.08 and E-a = -6.7 +/- 0.6 kJ mol(-1); for GeH2 + Et2GeH2, log A = -10.68 +/- 0.11 and E-a = -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.
机译：进行了时间分辨的3,4-二甲基-1-germacyclopent-3-ene的193 nm激光闪光光解所产生的二甲基亚砜GeH2的研究，以求得其与乙基和二乙基锗烷的双分子反应的速率常数。气相。在1-100 Torr的压力范围内，以SF6作为浴气，并在297-564 K的五个温度下对反应进行了研究。发现GeH2 + EtGeH3（399、486和564 K）的压力依赖性很小。高压速率常数给出以下Arrhenius参数：对于GeH2 + EtGeH3，log A = -10.75 +/- 0.08和E-a = -6.7 +/- 0.6 kJ mol（-1）;对于GeH2 + Et2GeH2，log A = -10.68 +/- 0.11和E-a = -6.95 +/- 0.80 kJ mol（-1）。这些与298 K下快速，近碰撞控制的缔合过程一致。RRKM模型计算在大多数情况下与所观察到的GeH2 + EtGeH3的压力依赖性一致。从这些结果中已提取出乙基取代基的作用，并且比SiH2 +甲基硅烷反应系列中类似的甲基取代基的作用要大得多。这与Ge-H插入的机理模型一致，在该模型中，中间体配合物对重排具有相当大的二级障碍。

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