DeSain John D, Valachovic Linda, Jusinski Leonard E, Taatjes Craig A
The Aerospace Corporation, El Segundo, California 90245-4691, USA.
J Chem Phys. 2006 Dec 14;125(22):224308. doi: 10.1063/1.2404673.
The reaction of trichlorosilane (HSiCl(3)) with atomic chlorine (Cl) has been investigated by using infrared kinetic spectroscopy of the HCl product. The overall second order rate constant for the reaction has been determined as a function of temperature by using pseudo-first-order kinetic methods. Formation of HCl (nu=0) was monitored on the (nu=1<--0) R(2) line at 2944.914 cm(-1) and that of HCl (nu=1) on the (nu=2<--1) R(2) line at 2839.148 cm(-1). The overall second order rate constant was determined to be (2.8+/-0.1)x10(-11) cm(3) molecule(-1) s(-1) at 296 K. The rate constant shows no pressure dependence and decreases slightly with increased temperature [k=(2.3+/-0.2)x10(-11)e((66+/-3)/T) cm(3) molecule(-1) s(-1)]. Substantial vibrational excitation is measured in the HCl product, with the fraction of HCl (nu=1)/HCl (total)=0.41+/-0.08. These observations are consistent with the reaction being a barrierless hydrogen abstraction reaction. The experimental results are supported by ab initio quantum chemical calculations that show the transition state for abstraction to lie below the energy of the reactants, in disagreement with previously published calculations.
通过对HCl产物进行红外动力学光谱研究，考察了三氯硅烷（HSiCl₃）与氯原子（Cl）的反应。采用准一级动力学方法，测定了该反应的总二级速率常数随温度的变化关系。在2944.914 cm⁻¹处的（ν = 1 ← 0）R(2)谱线上监测HCl（ν = 0）的生成，在2839.148 cm⁻¹处的（ν = 2 ← 1）R(2)谱线上监测HCl（ν = 1）的生成。在296 K时，测定的总二级速率常数为(2.8 ± 0.1)×10⁻¹¹ cm³·分子⁻¹·s⁻¹。该速率常数与压力无关，且随温度升高略有下降[k = (2.3 ± 0.2)×10⁻¹¹e((66 ± 3)/T) cm³·分子⁻¹·s⁻¹]。在HCl产物中测得大量的振动激发，HCl（ν = 1）/HCl（总量）的比例为0.41 ± 0.08。这些观察结果与该反应为无势垒氢提取反应一致。从头算量子化学计算支持了实验结果，计算表明提取反应的过渡态低于反应物的能量，这与之前发表的计算结果不同。
