取代氮氧自由基中氢键相互作用的理论研究,New Journal of Chemistry

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取代氮氧自由基中氢键相互作用的理论研究
New Journal of Chemistry ( IF 2.7 ) Pub Date : 2021-1-25 , DOI: 10.1039/d0nj05362g
Thufail M. Ismail _{1,

2,

3,

4} , Neetha Mohan _{1,

5,

6,

7,

8} , P. K. Sajith _{1,

2,

3,

4}

Affiliation

氮自由基与各种电子受体的分子间NO⋯H氢键键合说明了其有趣的性能和关键应用。在这项工作中，我们对由以HF，H ₂ O和CH ₄为电子受体的氮氧自由基形成的分子间NO⋯H氢键进行了全面和定量的理论分析。根据围绕氮氧化物氧原子的分子静电势的绝对最小值（V _min）评估氮氧化物自由基的电子效应，并将其与亚氨氧基自由基的电子效应进行比较。观测到的V _min值清楚地反映出存在于氮氧自由基基团结构中的取代基的给电子和吸电子特征。因此，在V _min和相互作用能之间建立了线性关系（E _int）氮氧化物和亚氨基氧基的氢键配合物的值分子中的原子量子理论（QTAIM）分析表明，在具有给电子取代基的系统中，氢键的性质是密闭壳和共享相互作用的混合，而在具有吸电子取代基的系统中，氢键的性质大多是密闭壳。对称自适应扰动理论（SAPT）计算表明，氢键主要取决于NO⋯HF和NO⋯H ₂ O络合物中相互作用能的静电成分，而主要贡献者是分散在NOCHHCH _3中复合体。本文的结果表明，修饰氮氧化物自由基的结构基序中的取代基有助于微调其与电子受体的配合物中氢键相互作用的强度和性质。而且，利用分子静电势和QTAIM参数的拓扑特征，可以有效地完成对硝基自由基中氢键相互作用的强度和性质的定量。

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Theoretical study of hydrogen bonding interactions in substituted nitroxide radicals

Intermolecular NO⋯H hydrogen bonding of nitroxide radicals with various electron acceptors accounts for their interesting properties and key applications. In this work we have performed a comprehensive and quantitative theoretical analysis of the intermolecular NO⋯H hydrogen bonds formed by nitroxide radicals with HF, H₂O, and CH₄ as electron acceptors. The electronic effects of nitroxide radicals are assessed in terms of the absolute minimum of molecular electrostatic potential (V_min) around nitroxide oxygen atom and compared with those of iminoxyl radicals. The observed V_min values clearly reflect the electron donating and withdrawing features of the substituents present in the structural framework of nitroxide radicals. Accordingly a linear relationship has been established between V_min and interaction energy (E_int) values of hydrogen bonded complexes of both nitroxide and iminoxyl radicals. Quantum theory of atoms in molecules (QTAIM) analysis demonstrated that the nature of hydrogen bonding in systems with electron donating substituents is a mix of closed shell and shared interactions, while it is mostly closed shell in systems with electron withdrawing substituents. Symmetry-adapted perturbation theory (SAPT) calculations show that the hydrogen bonds are largely dependent on electrostatic components of the interaction energy in NO⋯HF and NO⋯H₂O complexes, whereas the dominant contributor is dispersion in NO⋯HCH₃ complexes. The results herein suggest that modifying the substituents in the structural motif of nitroxide radicals helps to fine-tune the strength and nature of hydrogen bonding interactions in their complexes with electron acceptors. Moreover, quantification of the strength and nature of the hydrogen bonding interactions in nitroxide radicals can be effectively done with topological features of molecular electrostatic potential and QTAIM parameters.

更新日期：2021-02-15

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