Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37 Bratislava, Slovakia.
Int J Mol Sci. 2023 Feb 8;24(4):3447. doi: 10.3390/ijms24043447.
A test set of -tetrasubstituted -phenylenediamines are experimentally explored using ESR (electron spin resonance) spectroscopy and analysed from a computational standpoint thereafter. This computational study aims to further aid structural characterisation by comparing experimental ESR hyperfine coupling constants (hfccs) with computed values calculated using ESR-optimised "J-style" basis sets (6-31G(d,p)-J, 6-31G(d,p)-J, 6-311++G(d,p)-J, pcJ-1, pcJ-2 and cc-pVTZ-J) and hybrid-DFT functionals (B3LYP, PBE0, TPSSh, ωB97XD) as well as MP2. PBE0/6-31g(d,p)-J with a polarised continuum solvation model (PCM) correlated best with the experiment, giving an 2 value of 0.8926. A total of 98% of couplings were deemed satisfactory, with five couplings observed as outlier results, thus degrading correlation values significantly. A higher-level electronic structure method, namely MP2, was sought to improve outlier couplings, but only a minority of couples showed improvement, whilst the remaining majority of couplings were negatively degraded.
实验探索了一组 -四取代- 苯二胺，并从计算角度对其进行了分析。这项计算研究旨在通过将实验电子自旋共振（ESR）超精细耦合常数（hfccs）与使用 ESR 优化的“J 型”基组（6-31G(d,p)-J、6-31G(d,p)-J、6-311++G(d,p)-J、pcJ-1、pcJ-2 和 cc-pVTZ-J）和杂化密度泛函理论（B3LYP、PBE0、TPSSh、ωB97XD）以及 MP2 计算值进行比较，来进一步辅助结构表征。其中，PBE0/6-31g(d,p)-J 与极化连续溶剂模型（PCM）的相关性最好，实验值为 0.8926。总共有 98%的耦合被认为是令人满意的，其中五个耦合被视为异常值结果，从而显著降低了相关值。因此，我们寻求使用更高水平的电子结构方法，即 MP2，来改善异常耦合，但只有少数的耦合显示出改善，而其余大多数的耦合则出现了负向退化。
