Koziel Alexandra C, Bortoli Marco, Tremblay Matthew, Zhao Yilun, Orian Laura, Yang Zhongyue J, Schley Nathan D, Macdonald Janet E
Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Lane, Nashville, Tennessee 37240, United States.
Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Via Marzolo 1, 35131 Padova, Italy.
Inorg Chem. 2024 Jul 1;63(26):12063-12072. doi: 10.1021/acs.inorgchem.4c01025. Epub 2024 Jun 14.
Notable thermal shifts in diselenides have been documented in Se NMR for more than 50 years, but no satisfactory explanation has been found. Here, five hypotheses are considered as possible explanations for the large temperature dependence of the Se chemical shifts of diaryl and dialkyl diselenides compared to monoselenides and selenols. Density functional theory calculations are provided to bolster hypotheses and better understand the effects of barrier height and dipole energies. It is proposed that the temperature dependence of diselenide Se NMR chemical shifts is due to rotation around the Se-Se bond and sampling of twisted conformers at higher temperatures. The molecular twisting is solvent dependent; here, DMSO- and toluene- were evaluated. No correlation was established between -substituents on diaryl diselenides and the magnitude of the change in the Se NMR shift (Δδ) with temperature.
50多年来，硒核磁共振（Se NMR）已记录到二硒化物中显著的热位移，但尚未找到令人满意的解释。本文考虑了五种假设，作为解释二芳基和二烷基二硒化物与单硒化物和硒醇相比，其硒化学位移对温度有较大依赖性的可能原因。通过密度泛函理论计算来支持这些假设，并更好地理解势垒高度和偶极能的影响。本文提出，二硒化物Se NMR化学位移的温度依赖性是由于围绕Se-Se键的旋转以及在较高温度下扭曲构象的采样。分子扭曲取决于溶剂；本文评估了二甲基亚砜（DMSO）和甲苯。二芳基二硒化物上的取代基与Se NMR位移随温度变化的幅度（Δδ）之间未建立相关性。
