Institute of Organic Chemistry, Polish Academy of Sciences, 01-224 Warszawa, Kasprzaka 44, Poland.
Centre for Theoretical and Computational Chemistry, University of Tromso̸-The Arctic University of Norway, N-9037 Tromso̸, Norway.
J Chem Phys. 2013 Dec 21;139(23):234302. doi: 10.1063/1.4840295.
The spin-rotation and nuclear magnetic shielding constants are analysed for both nuclei in the HCl molecule. Nonrelativistic ab initio calculations at the CCSD(T) level of approximation show that it is essential to include relativistic effects to obtain spin-rotation constants consistent with accurate experimental data. Our best estimates for the spin-rotation constants of (1)H(35)Cl are CCl = -53.914 kHz and C(H) = 42.672 kHz (for the lowest rovibrational level). For the chlorine shielding constant, the ab initio value computed including the relativistic corrections, σ(Cl) = 976.202 ppm, provides a new absolute shielding scale; for hydrogen we find σ(H) = 31.403 ppm (both at 300 K). Combining the theoretical results with our new gas-phase NMR experimental data allows us to improve the accuracy of the magnetic dipole moments of both chlorine isotopes. For the hydrogen shielding constant, including relativistic effects yields better agreement between experimental and computed values.
对 HCl 分子中的两个核的自旋-转动和核磁屏蔽常数进行了分析。在 CCSD(T)水平的近似相对论非相对论从头算表明，要获得与精确实验数据一致的自旋-转动常数，必须包括相对论效应。我们对（1）H（35）Cl 的自旋-转动常数的最佳估计值为 CCl = -53.914 kHz 和 C（H）= 42.672 kHz（对于最低的振转能级）。对于氯的屏蔽常数，包括相对论修正在内的从头算值 σ（Cl）= 976.202 ppm，提供了新的绝对屏蔽标度；对于氢，我们发现 σ（H）= 31.403 ppm（均在 300 K 时）。将理论结果与我们新的气相 NMR 实验数据相结合，使我们能够提高两个氯同位素的磁偶极矩的准确性。对于氢的屏蔽常数，包括相对论效应可以使实验值和计算值之间更好地吻合。
