Houghton Adrian Y, Autrey Tom
Pacific Northwest National Laboratory , 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352 United States.
J Phys Chem A. 2017 Nov 22;121(46):8785-8790. doi: 10.1021/acs.jpca.7b08582. Epub 2017 Nov 9.
The mechanism of H heterolysis by the frustrated Lewis pair of B(CF) and P(mes) was investigated by isothermal reaction calorimetry in the temperature range from 30 to 90 °C. The experimental heat curves were modeled in Berkeley Madonna to obtain both kinetic and thermodynamics data simultaneously. The H activation reaction is treated as a single, termolecular step with a rate constant of 0.61 M s at 303 K with an exothermic enthalpy of reaction, ΔH = -141 kJ/mol. An Eyring analysis gave activation parameters of ΔH = 13.6(9) kJ mol and ΔS = -204(85) J K mol. Using D gas in place of H gas provided an opportunity to measure the relative rates of D versus H heterolysis to yield a the kinetic isotope effect, KIE = 1.1(1).
通过等温反应量热法在30至90°C的温度范围内研究了由B(CF)和P(mes)的受阻路易斯对引发的H异裂反应机理。在伯克利圣母软件中对实验热曲线进行建模，以同时获得动力学和热力学数据。H活化反应被视为一个单一的三分子步骤，在303K时速率常数为0.61 M⁻¹ s⁻¹，反应焓变放热，ΔH = -141 kJ/mol。艾林分析得出活化参数为ΔH = 13.6(9) kJ mol⁻¹和ΔS = -204(85) J K⁻¹ mol⁻¹。用D₂气体代替H₂气体提供了一个测量D异裂与H异裂相对速率的机会，以产生动力学同位素效应，KIE = 1.1(1)。
