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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Shielding and indirect spin-spin coupling tensors in the presence of a heavy atom: An experimental and theoretical study of bis(phenylethynyl)mercury
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Shielding and indirect spin-spin coupling tensors in the presence of a heavy atom: An experimental and theoretical study of bis(phenylethynyl)mercury

机译：重原子存在下的屏蔽和间接自旋-自旋耦合张量：双（苯基乙炔基）汞的实验和理论研究

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Magnetic shielding and indirect spin-spin coupling phenomena are tensorial properties and both their isotropic and anisotropic parts do affect NMR spectra. The involved interaction tensors, σ? and ?, can nowadays be theoretically calculated, although the reliability of such methods in the case of anisotropic parameters, δσ and δJ, in systems involving heavy nuclei, yet demands testing. In this communication the results of the experimental and theoretical investigations of bis(phenylethynyl)mercury (I) labeled with ~(13)C isotope at positions neighboring Hg are reported. The theoretical calculations of molecular geometry and values of NMR parameters for I have been performed by the ZORA/DFT method, including the relativistic scalar and spin-orbit coupling contributions, using the PBE0 functional and TZP (or jcpl) basis set. These values have been confronted with the experimentally measured ones. The isotropic parameters have been measured by the standard ~(13)C and ~(199)Hg NMR spectra. The shielding anisotropies for the atoms in the central part of molecule I have been determined in a liquid sample using magnetic relaxation measurements. The relaxation data have been interpreted within the rotational diffusion theory, assuming the symmetrical top reorientation model. The anisotropies of one-bond ~(13)C- ~(199)Hg and two-bond ~(13)C-Hg- ~(13)C spin-spin couplings have been determined exploiting the temperature-dependent ~(13)C NMR spectra of I in the ZLI1167 liquid-crystal phase. We have found that our theoretical calculations reproduce experimental values of both isotropic and anisotropic NMR parameters very well.
机译：磁屏蔽和间接自旋-自旋耦合现象是张量性质，它们的各向同性和各向异性部分的确会影响NMR光谱。所涉及的相互作用张量σ？尽管在涉及重核的系统中各向异性参数δσ和δJ的情况下，这种方法的可靠性，但仍需要进行测试，因此，理论上可以如今进行计算。在此通讯中，报道了在Hg附近的位置用〜（13）C同位素标记的双（苯基乙炔基）汞（I）的实验和理论研究的结果。 I的分子几何结构和NMR参数值的理论计算已通过ZORA / DFT方法进行，包括相对论性标量和自旋轨道耦合贡献，使用PBE0功能和TZP（或jcpl）基础集。这些值已与实验测量的值相对。各向同性参数已通过标准〜（13）C和〜（199）Hg NMR光谱测量。使用磁弛豫测量已经确定了液体样品中分子I中心部分原子的屏蔽各向异性。假设对称的顶部重新定向模型，在旋转扩散理论中已经解释了弛豫数据。利用温度相关的〜（13）来确定一键〜（13）C-〜（199）Hg和二键〜（13）C-Hg-〜（13）C自旋自旋偶合的各向异性。 ZLI1167液晶相中I的13 C NMR光谱。我们发现，我们的理论计算可以很好地再现各向同性和各向异性NMR参数的实验值。

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