Komorovsky Stanislav, Jakubowska Katarzyna, Świder Paweł, Repisky Michal, Jaszuński Michał
Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava 845 36, Slovakia.
Faculty of Chemistry, University of Warsaw, Pasteura 1, Warszawa 02-093, Poland.
J Phys Chem A. 2020 Jun 25;124(25):5157-5169. doi: 10.1021/acs.jpca.0c02807. Epub 2020 Jun 12.
An unambiguous assignment of coupling pathways plays an important role in the description and rationalization of NMR indirect spin-spin coupling constants (SSCCs). Unfortunately, the SSCC analysis and visualization tools currently available to quantum chemists are restricted to nonrelativistic theory. Here, we present the theoretical foundation for novel relativistic SSCC visualization techniques based on analysis of the SSCC densities and the first-order current densities induced by the nuclear magnetic dipole moments. Details of the implementation of these techniques in the ReSpect program package are discussed. Numerical assessments are performed on through-space SSCCs, and we choose as our examples the heavy-atom Se-Se, Se-Te, and Te-Te coupling constants in three similar molecules for which experimental data are available. SSCCs were calculated at the nonrelativistic, scalar relativistic, and four-component relativistic density functional levels of theory. Furthermore, with the aid of different visualization methods, we discuss the interpretation of the relativistic effects, which are sizable for Se-Se, very significant for Se-Te, and cannot be neglected for Te-Te couplings. A substantial improvement of the theoretical SSCC values is obtained by also considering the molecular properties of a second conformation.
耦合路径的明确归属在核磁共振间接自旋 - 自旋耦合常数（SSCCs）的描述和合理化中起着重要作用。不幸的是，量子化学家目前可用的SSCC分析和可视化工具仅限于非相对论理论。在此，我们基于对SSCC密度和由核磁偶极矩诱导的一阶电流密度的分析，提出了新型相对论SSCC可视化技术的理论基础。讨论了这些技术在ReSpect程序包中的实现细节。对空间贯穿SSCCs进行了数值评估，我们选择了三个有实验数据的类似分子中的重原子Se - Se、Se - Te和Te - Te耦合常数作为例子。在非相对论、标量相对论和四分量相对论密度泛函理论水平上计算了SSCCs。此外，借助不同的可视化方法，我们讨论了相对论效应的解释，这些效应对于Se - Se耦合相当大，对于Se - Te耦合非常显著，对于Te - Te耦合不可忽略。通过考虑第二种构象的分子性质，理论SSCC值得到了显著改善。
