Gonzales Jason M, Pak Chaeho, Cox R Sidney, Allen Wesley D, Schaefer III Henry F, Császár Attila G, Tarczay György
Center for Computational Quantum Chemistry University of Georgia, Athens, Georgia 30602-2525, USA.
Chemistry. 2003 May 23;9(10):2173-92. doi: 10.1002/chem.200204408.
The energetics of the stationary points of the gas-phase reactions CH(3)X+F(-)-->CH(3)F+X(-) (X=F, Cl, CN, OH, SH, NH(2) and PH(2)) have been definitively computed using focal point analyses. These analyses entailed extrapolation to the one-particle limit for the Hartree-Fock and MP2 energies using basis sets of up to aug-cc-pV5Z quality, inclusion of higher-order electron correlation [CCSD and CCSD(T)] with basis sets of aug-cc-pVTZ quality, and addition of auxiliary terms for core correlation and scalar relativistic effects. The final net activation barriers for the forward reactions are: E (b/F,F)=-0.8, E (b/F, Cl)=-12.2, E (b/F,OH)=+13.6, E b/F,OH=+16.1, E b/F,SH=+2.8, Eb/F, NH=+32.8, and E b/F,PH =+19.7 kcal x mol(-1). For the reverse reactions E b/F,F= -0.8, Eb/Cl,F =+18.3, E b/CN,F=+12.2, E b/OH,F =-1.8, E b/SH,F =+13.2, E b/NH(2),=-1.5, and E b/PH(2) =+9.6 kcal x mol(-1). The change in energetics between the CCSD(T)/aug-cc-pVTZ reference prediction and the final extrapolated focal point value is generally 0.5-1.0 kcal mol(-1). The inclusion of a tight d function in the basis sets for second-row atoms, that is, utilizing the aug-cc-pV(X+d)Z series, appears to change the relative energies by only 0.2 kcal x mol(-1). Additionally, several decomposition schemes have been utilized to partition the ion-molecule complexation energies, namely the Morokuma-Kitaura (MK), reduced variational space (RVS), and symmetry adapted perturbation theory (SAPT) techniques. The reactant complexes fall into two groups, mostly electrostatic complexes (FCH(3).F(-) and ClCH(3).F(-)), and those with substantial covalent character (NCCH(3).F(-), CH(3)OH.F(-), CH(3)SH.F(-), CH(3)NH(2).F(-) and CH(3)PH(2).F(-)). All of the product complexes are of the form FCH(3).X(-) and are primarily electrostatic.
已使用焦点分析精确计算了气相反应CH(3)X + F(-) --> CH(3)F + X(-)（X = F、Cl、CN、OH、SH、NH(2)和PH(2)）驻点的能量学。这些分析包括使用高达aug-cc-pV5Z质量的基组将Hartree-Fock和MP2能量外推到单粒子极限，使用aug-cc-pVTZ质量的基组包含高阶电子相关[CCSD和CCSD(T)]，以及添加核心相关和标量相对论效应的辅助项。正向反应的最终净活化能垒为：E (b/F,F)= -0.8，E (b/F,Cl)= -12.2，E (b/F,OH)= +13.6，E b/F,OH = +16.1，E b/F,SH = +2.8，Eb/F, NH = +32.8，以及E b/F,PH = +19.7 kcal·mol(-1)。对于逆向反应，E b/F,F = -0.8，Eb/Cl,F = +18.3，E b/CN,F = +12.2，E b/OH,F = -1.8，E b/SH,F = +13.2，E b/NH(2), = -1.5，以及E b/PH(2) = +9.6 kcal·mol(-1)。CCSD(T)/aug-cc-pVTZ参考预测与最终外推焦点值之间的能量学变化通常为0.5 - 1.0 kcal·mol(-1)。在第二周期原子的基组中包含紧密d函数，即使用aug-cc-pV(X + d)Z系列，似乎仅使相对能量改变0.2 kcal·mol(-1)。此外，已使用几种分解方案来划分离子 - 分子络合能，即Morokuma-Kitaura（MK）、约化变分空间（RVS）和对称适配微扰理论（SAPT）技术。反应物络合物分为两组，主要是静电络合物（FCH(3).F(-)和ClCH(3).F(-)），以及具有大量共价特征的络合物（NCCH(3).F(-)、CH(3)OH.F(-)、CH(3)SH.F(-)、CH(3)NH(2).F(-)和CH(3)PH(2).F(-)）。所有产物络合物均为FCH(3).X(-)形式，且主要是静电的。
