Activation energies and reaction energetics for 1,3-dipolar cycloadditions of hydrazoic acid with C-C and C-N multiple bonds from high-accuracy and density functional quantum mechanical calculations
Activation energies and reaction energetics for 1,3-dipolar cycloadditions of hydrazoic acid with C-C and C-N multiple bonds from high-accuracy and density functional quantum mechanical calculations
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DOI：
10.1002/hlca.200590134
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发表时间：
2005-01-01
影响因子：
1.8
通讯作者：
Houk, KN
中科院分区：
文献类型：
--
作者：
Jones, GO;Ess, DH;Houk, KN
利用高精度的CBS-QB3方法，以及B3LYP和mPW1K密度泛函，探讨了水合苯甲酸（HN3）与乙烯、乙炔、甲醛二胺（H2C=NH）和HCN的反应。CBS-QB3预测了水合苯甲酸与乙烯、乙炔、甲醛胺和HCN反应的活化能非常相似，分别为19.0、19.0、21.6和25.2 kcal/mol。经计算，乙烯生成三唑啉的反应焓为-21.5，乙炔生成芳香三唑的反应焓为-63.7 kcal/mol。甲甲醛二胺生成四唑啉的反应焓为-8 kcal/mol (δ G(rxn) = +5.6 kcal/mol)， HCN生成四唑的反应焓为-23.0 kcal/mol。这些过程的能量学趋势是由过渡态和加合物的西格玛键能的差异以及将苯甲酸扭曲成其过渡态几何形状所需的能量来解释的。密度泛函预测的活化焓值与CBS-QB3的预测结果较为一致。结果与CBS-QB3的结果相差约1-2千卡/摩尔。mPW1K在预测所有反应的反应焓时存在显著误差。
The reactions of hydrazoic acid (HN3) with ethene, acetylene, formaldimine (H2C=NH), and HCN were explored with the high-accuracy CBS-QB3 method, as well as with the B3LYP and mPW1K density functionals. CBS-QB3 predicts that the activation energies for the reactions of hydrazoic acid with ethylene, acetylene, formaldimine, and HCN have remarkably similar activation enthalpies of 19.0, 19.0, 21.6, and 25.2 kcal/mol, respectively. The reactions are calculated to have reaction enthalpies of -21.5 for triazoline formation from ethene, and -63.7 kcal/mol for formation of the aromatic triazole from acetylene. The reaction to form tetrazoline from formaldimine has a reaction enthalpy of -8 kcal/mol (Delta G(rxn) = +5.6 kcal/mol), and the formation of tetrazole from HCN has a reaction enthalpy of -23.0 kcal/mol. The trends in the energetics of these processes are rationalized by differences in sigma-bond energies in the transition states and adducts, and the energy required to distort hydrazoic acid to its transition-state geometry. The density functionals predict activation enthalpies that are in relatively good agreement with CBS-QB3. the results differing from CBS-QB3 results by ca. 1-2 kcal/mol. Significant errors are revealed for mPW1K in predicting the reaction enthalpies for all reactions.