Abstract High-resolution (600 MHz) 1H and 13C chemical shift and 2D HETCOR NMR spectra of [60]PCBM were recorded. Resonances from every carbon atom of the ester, phenyl and cyclo-fullerenyl groups, were fully accounted. Assignments of the fullerene cyclopropa-ring, and all phenyl and ester carbons to their respective resonances were based on a HETCOR 2D NMR spectrum. Remaining fullerene assignments were made to a high level of confidence with the aid of an ωB97X hybrid HF/DFT simulation of the 13C NMR spectrum employing a triple zeta Dunning-type basis set. The best result was obtained with the range-separation parameter ω set effectively to zero. This indicates that the fraction of HF in the HF/DFT hybrid at very short range is the dominant factor in achieving good NMR results, that ωB97X with its 15.77% HF fraction at rij = 0 seems very well suited, and that allowing the HF fraction to increase with range is not particularly beneficial. The resulting spectrum had a remarkable qualitative agreement with experiment with a very low mean absolute error for fullerene carbons of 0.09 ppm, which was considerably lower than the 0.28 ppm of the more commonly used B3LYP/6-31G(d,p) method.

中文翻译：

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富勒烯衍生物 [60] PCBM 的表征，通过高场碳和二维 NMR 光谱，结合 DFT 模拟

摘要 记录了 [60]PCBM 的高分辨率 (600 MHz) 1H 和 13C 化学位移和 2D HETCOR NMR 光谱。来自酯、苯基和环富勒烯基团的每个碳原子的共振被充分考虑。富勒烯环丙环以及所有苯基和酯碳对其各自共振的分配基于 HETCOR 2D NMR 光谱。借助采用三重 zeta Dunning 型基组的 13C NMR 光谱的 ωB97X 混合 HF/DFT 模拟，剩余的富勒烯分配具有高置信度。最好的结果是在距离分离参数 ω 有效设置为零的情况下获得的。这表明在极短距离的 HF/DFT 混合物中 HF 的分数是获得良好 NMR 结果的主要因素，即 ωB97X 及其 15。rij = 0 时的 77% HF 分数似乎非常适合，并且允许 HF 分数随范围增加并不是特别有益。所得光谱与实验具有显着的定性一致性，富勒烯碳的平均绝对误差非常低，为 0.09 ppm，远低于更常用的 B3LYP/6-31G(d,p) 方法的 0.28 ppm。