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首页> 外文期刊>Chemistry: A European journal >DFT Study of the NMR Properties of Xenon in Covalent Compounds and van der Waals Complexes-Implications for the Use of ~(129)Xe as a Molecular Probe
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DFT Study of the NMR Properties of Xenon in Covalent Compounds and van der Waals Complexes-Implications for the Use of ~(129)Xe as a Molecular Probe

机译：DFT研究氙在共价化合物和范德华配合物中的NMR性质-对〜（129）Xe作为分子探针的意义

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摘要

The NMR properties (chemical shift and spin-spin coupling constants) of ~(129)Xe in covalent compounds and weakly bound complexes have been investigated by DFT methods including relativistic effects. For covalent species, a good agreement between experimental and calculated results is achieved without scalar relativistic effects, but their inclusion (with a triple-zeta, double-polarization basis set) leads to some improvement in the quality of the correlation. The spin-orbit coupling term has a significant effect on the shielding constant, but makes a small contribution to the chemical shift. Coupling constants contain substantial contributions from the Fermi contact and paramagnetic spin-orbit terms; unlike light nuclei the spin-dipole term is also large, whereas the diamagnetic spin-orbit term is negligible. For van der Waals dimers, the dependence of the xenon chemical shift and anisotropy is calculated as a function of the distance. Small (<1 Hz) but non-negligible through space coupling constants between ~(129)Xe and ~(13)C or ~1H are predicted. Much larger couplings, of the order of few Hz, are calculated between xenon and ~(17)O in a model silicate residue.
机译：已通过DFT方法（包括相对论效应）研究了共价化合物和弱结合复合物中〜（129）Xe的NMR特性（化学位移和自旋-自旋-旋转耦合常数）。对于共价物种，在没有标量相对论效应的情况下就可以在实验结果和计算结果之间达成良好的一致性，但是将它们包括在内（具有三重ζ，双极化基集）会提高相关质量。自旋轨道耦合项对屏蔽常数有很大影响，但对化学位移的贡献很小。耦合常数包含费米接触和顺磁自旋轨道项的大量贡献。与光核不同，自旋偶极子项也很大，而反磁自旋轨道项可忽略不计。对于范德华二聚体，氙化学位移和各向异性的相关性将作为距离的函数进行计算。可以预测〜（129）Xe与〜（13）C或〜1H之间的空间耦合常数很小（<1 Hz），但不可忽略。在模型硅酸盐残渣中，氙和〜（17）O之间计算出了几赫兹量级的更大耦合。

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