Ateşin Tülay A, Jones William D, Atesin Abdurrahman C
School of Earth, Environmental and Marine Sciences, The University of Texas Rio Grande Valley, Edinburg, Texas 78541, United States.
Department of Chemistry, University of Rochester, Rochester, New York 14627, United States.
Inorg Chem. 2023 Dec 4;62(48):19698-19705. doi: 10.1021/acs.inorgchem.3c03065. Epub 2023 Nov 21.
A recent study of the oxidative addition of zerovalent Ni to the C-CN bond of F-substituted benzonitriles showed significantly increased stabilization of the C-CN oxidative addition products with -F groups (-6.6 kcal/mol per -F) compared to -F groups (-1.8 kcal/mol per -F). To answer the question of whether this is an -F effect or an effect, in this study the effect of CF and CH groups on the oxidative addition of the [Ni(dmpe)] fragment [dmpe = 1,2-bis(dimethylphosphino)ethane] to the C-CN bond of benzonitriles has been studied. A density functional theory study of the reaction pathway between η-CN complexes and the C-CN oxidative addition products shows stabilization of the C-CN oxidative addition product with the electron-withdrawing CF group and destabilization with the electron-donating CH group in both tetrahydrofuran and toluene. There is a slightly larger effect with CF (-7.4 kcal/mol) than with F. However, due to steric crowding, two CF groups did not show considerably more stabilization than one -CF group. There is a linear relationship between Δ and the number of groups (2.0 kcal/mol stabilization per -CF and 0.8 kcal/mol destabilization per -CH). On the basis of natural population analysis, as the C-CN bond becomes more polarized, the stability of the C-CN oxidative addition products with respect to the η-CN complexes increases.
最近一项关于零价镍与氟取代苯甲腈的C-CN键进行氧化加成反应的研究表明，与氯取代基（每个氯取代基为-1.8 kcal/mol）相比，带有氟取代基（每个氟取代基为-6.6 kcal/mol）的C-CN氧化加成产物的稳定性显著提高。为了回答这是氟效应还是氯效应的问题，在本研究中，研究了CF和CH基团对[Ni(dmpe)]片段[dmpe = 1,2-双(二甲基膦基)乙烷]与苯甲腈的C-CN键进行氧化加成反应的影响。对η-CN配合物与C-CN氧化加成产物之间反应途径的密度泛函理论研究表明，在四氢呋喃和甲苯中，吸电子的CF基团使C-CN氧化加成产物稳定，而给电子的CH基团使其不稳定。CF（-7.4 kcal/mol）的效应比F略大。然而，由于空间拥挤，两个CF基团的稳定作用并不比一个-CF基团显著得多。Δ与CF基团数量之间存在线性关系（每个-CF基团稳定2.0 kcal/mol，每个-CH基团不稳定0.8 kcal/mol）。基于自然布居分析，随着C-CN键的极化程度增加，C-CN氧化加成产物相对于η-CN配合物的稳定性提高。
