Relativistic Force Field: Parametrization of 13C鈥?H Nuclear Spin鈥揝pin Coupling Constants

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• 作者：Andrei G. Kutateladze ; Olga A. Mukhina
• 刊名：Journal of Organic Chemistry
• 出版年：2015
• 出版时间：November 6, 2015
• 年：2015
• 卷：80
• 期：21
• 页码：10838-10848
• 全文大小：376K
• ISSN：1520-6904

文摘

Previously, we reported a reliable DU8 method for natural bond orbital (NBO)-aided parametric scaling of Fermi contacts to achieve fast and accurate prediction of proton鈥損roton spin鈥搒pin coupling constants (SSCC) in ¹H NMR. As sophisticated NMR experiments for precise measurements of carbon鈥損roton SSCCs are becoming more user-friendly and broadly utilized by the organic chemistry community to guide and inform the process of structure determination of complex organic compounds, we have now developed a fast and accurate method for computing ¹³C鈥?sup>1H SSCCs. Fermi contacts computed with the DU8 basis set are scaled using selected NBO parameters in conjunction with empirical scaling coefficients. The method is optimized for inexpensive B3LYP/6-31G(d) geometries. The parametric scaling is based on a carefully selected training set of 274 (³J), 193 (²J), and 143 (¹J) experimental ¹³C鈥?sup>1H spin鈥搒pin coupling constants reported in the literature. The DU8 basis set, optimized for computing Fermi contacts, which by design had evolved from optimization of a collection of inexpensive 3-21G*, 4-21G, and 6-31G(d) bases, offers very short computational (wall) times even for relatively large organic molecules containing 15鈥?0 carbon atoms. The most informative SSCCs for structure determination, i.e., ³J, were computed with an accuracy of 0.41 Hz (rmsd). The new unified approach for computing ¹H鈥?sup>1H and ¹³C鈥?sup>1H SSCCs is termed 鈥淒U8c鈥?