Electrostatically tuning radical addition and atom abstraction reactions with distonic radical ions

This data set accompanies the manuscript Electrostatically tuning radical addition and atom abstraction reactions with distonic radical ions by Oisin J. Shiels and Samuel C. Brydon, Berwyck L. J. Poad, David L. Marshall, Sevan D. Houston, Hui Xing, Paul V. Bernhardt, G. Paul Savage, Craig M. Williams, David G. Harman, Benjamin B. Kirk, Gabriel da Silva, Stephen J. Blanksby and Adam J. Trevitt (submitted to Chemical Science).

Abstract: Although electrostatic catalysis can enhance the kinetics and selectivity of reactions to produce greener synthetic processes, the highly directional nature of electrostatic interactions has limited widespread application. In this study, the influence of oriented electric fields (OEF) on radical addition and atom abstraction reactions are systematically explored with ion-trap mass spectrometry using structurally diverse distonic radical ions that maintain spatially separated charge and radical moieties. When installed on rigid molecular scaffolds, charged functional groups lock the magnitude and orientation of the internal electric field with respect to the radical site, creating an OEF which tunes the reactivity across the set of gas-phase carbon-centred radical reactions. In the first case, OEFs predictably accelerate and decelerate the rate of molecular oxygen addition to substituted phenyl, adamantyl, and cubyl radicals, depending on the polarity of the charged functional group and dipole orientation. In the second case, OEFs modulate competition between chlorine and hydrogen atom abstraction from chloroform based on interactions between charge polarity, dipole orientation, and radical polarizability. Importantly, this means the same charge polarity can induce different changes to reaction selectivity. Quantum chemical calculations of these reactions with DSD-PBEP86-D3(BJ)/aug-cc-pVTZ show correlations between the barrier heights and the experimentally determined reaction kinetics. Field effects are consistent between phenyl and cubyl scaffolds, pointing to through-space rather than through-bond field effects, congruent with computations showing that the same effects can be mimicked by point charges. These results experimentally demonstrate how internal OEFs generated by carefully placed charged functional groups can systematically control radical reactions.

Data file includes: experimental mass spectra files from kinetic experiments and output files from Gaussian calculations.

此数据集伴随论文《通过使用双电荷正离子调控自由基加成和原子抽象反应的电荷催化》（作者：Oisin J. Shiels 和 Samuel C. Brydon，Berwyck L. J. Poad，David L. Marshall，Sevan D. Houston，Hui Xing，Paul V. Bernhardt，G. Paul Savage，Craig M. Williams，David G. Harman，Benjamin B. Kirk，Gabriel da Silva，Stephen J. Blanksby 和 Adam J. Trevitt，提交至《化学科学》期刊）。摘要：尽管静电催化能够提升反应的动力学和选择性，从而促进绿色合成工艺的发展，但静电相互作用的强烈方向性限制了其广泛应用。在本研究中，通过使用离子阱质谱仪，系统性地探讨了定向电场（OEF）对自由基加成和原子抽象反应的影响，所用的结构多样化的双电荷正离子离子维持了空间上分离的电荷和自由基基团。当这些电荷基团被安装在刚性的分子支架上时，它们会锁定相对于自由基位的内部电场的幅度和方向，从而创建一个OEF，该OEF调节了一系列气相碳中心自由基反应的活性。在第一种情况下，OEF可以预测性地加速或减慢分子氧添加到取代苯、金刚烷和立方烷自由基的反应速率，这取决于电荷基团的极性和偶极取向。在第二种情况下，OEF调节了氯和氢原子从氯仿中抽象的竞争，这基于电荷极性、偶极取向和自由基极化率之间的相互作用。值得注意的是，相同的电荷极性可以引起反应选择性的不同变化。使用DSD-PBEP86-D3(BJ)/aug-cc-pVTZ量子化学计算这些反应，显示出势垒高度与实验确定的反应动力学之间的相关性。在苯和立方烷支架之间，场效应的一致性指向了空间效应而非键效应，与计算结果一致，计算结果显示相同的效应可以通过点电荷来模拟。这些结果实验性地展示了如何通过精心放置的电荷基团产生的内部OEF系统地控制自由基反应。数据文件包括：动力学实验的实验质谱文件和Gaussian计算输出文件。