Jaszuński Michał, Sauer Stephan P A, Faber Rasmus, Wilson David J D
Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44-52, 01-224 Warsaw, Poland.
Phys Chem Chem Phys. 2020 Sep 30;22(37):21350-21359. doi: 10.1039/d0cp02730h.
NMR shielding and spin-spin coupling constants of cis and trans isomers of FNNF have been determined to near-quantitative accuracy from ab initio calculations. The FNNF system, containing multiple N-F bonds and fluorine atoms, provides a severe test of computational methods. Coupled-cluster methods were used with large basis sets and complete basis set (CBS) extrapolations of the equilibrium geometry results, with vibrational and relativistic corrections. Shielding constants were calculated with basis sets as large as aug-cc-pCV7Z, together with coupled-cluster expansions up to CCSDT, at the all-electron CCSD(T)/aug-cc-pCVQZ optimized geometries. Spin-spin coupling constants have been determined with specialized versions of the correlation consistent basis sets ccJ-pVXZ, further augmented with diffuse functions. All-electron coupled-cluster methods up to CC3 were applied in these calculations. The results of this work highlight the application of state-of-the-art theoretical techniques, and provide the most accurate NMR properties of FNNF to date, which can serve to guide and supplement NMR experimentation.
通过从头算计算，已将FNNF顺式和反式异构体的核磁共振屏蔽常数和自旋-自旋耦合常数测定至接近定量的精度。包含多个N-F键和氟原子的FNNF体系对计算方法构成了严峻考验。耦合簇方法与大基组一起使用，并对平衡几何结构结果进行完整基组（CBS）外推，同时进行振动和相对论校正。屏蔽常数使用高达aug-cc-pCV7Z的基组进行计算，并在全电子CCSD(T)/aug-cc-pCVQZ优化几何结构下进行高达CCSDT的耦合簇展开。自旋-自旋耦合常数已使用相关一致基组ccJ-pVXZ的特殊版本确定，并进一步增加了弥散函数。在这些计算中应用了高达CC3的全电子耦合簇方法。这项工作的结果突出了最先进理论技术的应用，并提供了迄今为止FNNF最准确的核磁共振性质，可用于指导和补充核磁共振实验。
