构象灵活的过渡金属配合物中振动圆二色性增强
Vibrational Circular Dichroism enhancement in conformationally flexible transition metal complexes
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中文总结 AI 辅助
研究构象灵活的过渡金属配合物VCD光谱，扩展先前计算方法，以吉布斯自由能和电子激发能为拟合参数，能出色重现实验，证明DFT优化构象集冗余，可简化模型，还确认增强的对称选择性并制定选择规则。
中文摘要 AI 辅助
我们将先前开发的计算过渡金属配合物增强振动圆二色性（VCD）光谱的方法扩展到构象灵活性对重现和阐释实验光谱至关重要的体系。将吉布斯自由能和电子激发能都作为拟合参数，对于钴（II）双[N-（1-芳基乙基）-水杨醛亚胺基]席夫碱配合物，我们证明这些计算能出色地重现实验。重要结论是DFT优化的构象集在光谱上是冗余的，该模型可从18个构象简化为仅两个在金属中心具有相反手性（$\Lambda$/$\Delta$）的构象，且不影响理论与实验在VCD光谱以及$\Lambda$和$\Delta$构象上的总体分布的一致性。最后，我们通过数值确认了增强的对称选择性，并在相关的态叠加表达式框架内制定了相应的选择规则。
英文摘要
We extend our previously developed approach for calculating enhanced vibrational circular dichroism (VCD) spectra of transition-metal complexes to systems for which conformational flexibility is key to reproduce and elucidate experimental spectra. Treating both the Gibbs free energies and electronic excitation energies as fitting parameters, we show for Co(II)bis[N-(1-arylethyl)- salicylaldiminato] Schiff base complexes that these calculations can excellently reproduce the experiment. An important conclusion is that the DFT-optimized conformer set is spectrally redundant and that the model can be reduced from 18 conformers to only two conformers with opposite chirality at the metal center ($Λ$/$Δ$) without affecting the agreement between theory and experiment, both with respect to the VCD spectrum as well population distribution over the $Λ$ and $Δ$ conformers. Finally, we numerically confirm the symmetry-selective nature of the enhancement and formulate the corresponding selection rules within the framework of the pertaining Sum-Over-States expressions.
