Trac H Phuong, Le Huyen Trinh, Lin Ming-Chang
Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan.
Center for Emergent Functional Matter Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
J Phys Chem A. 2020 Dec 3;124(48):9923-9932. doi: 10.1021/acs.jpca.0c08665. Epub 2020 Nov 17.
The redox reactions of NH and CHNH with NO (NTO) have been studied by ab initio molecular orbital (MO) calculations at the UCCSD(T)∥UB3LYP/6-311+G(3df,2p) level of theory. These reactions are related to the well-known NTO-hydrazine(s) propellant systems. On the basis of the predicted potential energy surfaces, the mechanisms for these reactions were found to be similar to the hydrolysis of NTO and the hypergolic initiation reaction of the NTO-NH mixture, primarily controlled by the conversion of NTO to ONONO via very loose transition states (with NH and CHNH as spectators in the collision complexes) followed by the rapid attack of ONONO at the spectating molecules producing HNO and RNO (R = NH and CHNH). The predicted mechanism for the NH reaction compares closely with its isoelectronic process NTO + HO; similarly, the mechanism for the NTO + CHNH reaction also compares closely with its isoelectronic NTO + NHNH reaction. The kinetics for the formation of the final products, HNO + RNO (R = NH, OH, CHNH, and NH), were found to be weakly pressure-dependent at low temperatures and affected by the strengths of H-NH and H-OH but not in the RNH case. We have also compared the predicted rate constant for the oxidation of NH by NO with that for the analogous NH + NO recently reported by Sarkar and Bandyopadhyay [ , , 3564-3572] under troposphere conditions. The rate of the latter reaction was estimated to be 2 orders of magnitude slower than that of the NO reaction under troposphere conditions.
通过在UCCSD(T)∥UB3LYP/6 - 311 + G(3df,2p)理论水平下进行的从头算分子轨道（MO）计算，研究了NH和CHNH与NO（NTO）的氧化还原反应。这些反应与著名的NTO - 肼类推进剂系统有关。基于预测的势能面，发现这些反应的机理与NTO的水解以及NTO - NH混合物的自燃引发反应相似，主要由NTO通过非常松散的过渡态（在碰撞复合物中NH和CHNH作为旁观者）转化为ONONO来控制，随后ONONO迅速攻击旁观者分子生成HNO和RNO（R = NH和CHNH）。预测的NH反应机理与其等电子过程NTO + HO密切相关；同样，NTO + CHNH反应的机理也与其等电子的NTO + NHNH反应密切相关。发现最终产物HNO + RNO（R = NH、OH、CHNH和NH）形成的动力学在低温下对压力的依赖性较弱，并且受H - NH和H - OH强度的影响，但在RNH的情况下不受影响。我们还将预测的NO氧化NH的速率常数与Sarkar和Bandyopadhyay最近报道的对流层条件下类似的NH + NO的速率常数进行了比较。估计后一反应的速率在对流层条件下比NO反应的速率慢2个数量级。
