Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, Wood Lane, London W12 OBZ, UK.
Department of Chemistry, The University of Manchester, Manchester M13 9PL, UK.
Phys Chem Chem Phys. 2022 Aug 31;24(34):20409-20425. doi: 10.1039/d2cp02317b.
We report the evaluation of density-functional-theory (DFT) based procedures for predicting F NMR chemical shifts at modest computational cost for a range of molecules with fluorine bonds, to be used as a tool for assisting the characterisation of reaction intermediates and products and as an aid to identifying mechanistic pathways. The results for a balanced learning set of molecules were then checked using two further testing sets, resulting in the recommendation of the ωB97XD/aug-cc-pvdz DFT method and basis set as having the best combination of accuracy and computational time, with a RMS error of 3.57 ppm. Cationic molecules calculated without counter-anion showed normal errors, whilst anionic molecules showed somewhat larger errors. The method was applied to the prediction of the conformationally averaged F chemical shifts of 2,2,3,3,4,4,5,5-octafluoropentan-1-ol, in which gauche stereoelectronic effects involving fluorine dominate and to determining the position of coordination equilibria of fluorinated boranes as an aid to verifying the relative energies of intermediate species involved in catalytic amidation reactions involving boron catalysts.
我们报告了密度泛函理论（DFT）方法在预测氟键分子的 F NMR 化学位移方面的评估，该方法在适度的计算成本下可用于辅助反应中间体和产物的特征化，并作为识别反应机制途径的辅助工具。然后，使用另外两个测试集检查了平衡学习集分子的结果，结果推荐 ωB97XD/aug-cc-pvdz DFT 方法和基组具有最佳的准确性和计算时间组合，均方根误差为 3.57 ppm。未考虑抗衡阴离子的阳离子分子显示出正常的误差，而阴离子分子则显示出稍大的误差。该方法被应用于预测 2,2,3,3,4,4,5,5-八氟戊-1-醇的构象平均 F 化学位移，其中涉及氟的 gauche 立体电子效应占主导地位，并确定氟化硼烷的配位平衡位置，以验证涉及硼催化剂的酰胺化反应中中间物种的相对能量。
