Speaker
Description
Ab initio calculations of NMR shielding constants have made it possible to re-evaluate nuclear magnetic dipole moments from NMR experiments, offering a substantial improvement over traditional diamagnetic corrections.
In this work, we report accurate ab initio NMR shielding constants for selenium and tellurium compounds: (1) Se(CH$_3$)$_2$ and Te(CH$_3$)$_2$, which define the current NMR standards for these elements, and (2) the water-solvated anions SeO$_3^{2-}$ and TeO$_3^{2-}$, previously used to determine the magnetic moments of $^{77}$Se, $^{123}$Te, and $^{125}$Te nuclei. All key factors influencing NMR shielding—relativistic effects, electron correlation, and solvent interactions—are systematically analyzed. Relativistic effects are treated using four-component density functional theory (DFT), electron correlation is accounted for at the coupled-cluster level, and solvent effects are modeled through both implicit and explicit solvent approaches.
Using the computed shielding constants for the NMR standards Se(CH$_3$)$_2$ and Te(CH$_3$)$_2$, we re-derived the nuclear magnetic dipole moments and recommend the following updated values: $\mu$($^{77}$Se) = 0.53380(3)$\mu_N$, $\mu$($^{123}$Te) = –0.7341(1)$\mu_N$, and $\mu$($^{125}$Te) = –0.8850(1)$\mu_N$.
These revised magnetic dipole moments provide robust reference values for nuclear physics applications, particularly for high-precision spectroscopic measurements across isotopic series.
