Szűcs Tímea, Czakó Gábor
MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary.
Phys Chem Chem Phys. 2022 Aug 31;24(34):20249-20257. doi: 10.1039/d2cp03006c.
This electronic structure study reveals four exothermic and two endothermic reaction pathways of the F + CHNH system: the barrierless hydrogen abstraction from the methyl/amino group (HF + CHNH/CHNH), amino/methyl substitution (NH + CHF and CH + NHF) and hydrogen substitution from the two functional groups (H + CHFNH/CHNHF). The benchmark classical and adiabatic energies are obtained using a high-accuracy composite approach, where the gold-standard explicitly-correlated coupled cluster method (CCSD(T)-F12b) is applied with the correlation-consistent polarized valence quintuple-zeta F12 basis set (cc-pV5Z-F12) and further additive energy contributions. Considering indispensable post-(T) correlation, core correlation, scalar relativistic, spin-orbit and harmonic zero-point energy corrections, the obtained global minimum of the potential energy surface is the post-reaction CHNH⋯HF complex in the product channel. Although each substitution pathway has a high barrier, the energies of amino-substitution and methyl-hydrogen-substitution products are below the energy of the reactants, as well as the submerged-barrier hydrogen-abstraction pathways.
这项电子结构研究揭示了F + CHNH体系的四条放热反应途径和两条吸热反应途径：从甲基/氨基进行无障碍氢提取（HF + CHNH/CHNH）、氨基/甲基取代（NH + CHF和CH + NHF）以及从两个官能团进行氢取代（H + CHFNH/CHNHF）。使用高精度复合方法获得了基准经典能量和绝热能量，其中应用了金标准显式相关耦合簇方法（CCSD(T)-F12b）以及相关一致极化价五次zeta F12基组（cc-pV5Z-F12）和进一步的加性能量贡献。考虑到不可或缺的后（T）相关、核心相关、标量相对论、自旋轨道和谐波零点能量校正，所获得的势能面全局最小值是产物通道中的反应后CHNH⋯HF复合物。尽管每条取代途径都有很高的势垒，但氨基取代产物和甲基氢取代产物的能量低于反应物的能量，以及潜势垒氢提取途径的能量。
