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Link between Spin-Orbit Relativity and Magnetically Induced Current Densities in Heavy-Atom Hydrides: trans-Ligand
Daniel Blasco1, Jan Novotný1,2, James R Asher3
1CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 62500 Brno, Czechia.
JACS Au
|June 26, 2026
Summary
Relativistic spin-orbit coupling significantly impacts magnetically induced current density (MICD) in heavy-atom hydrides. This electronic effect, not metal-hydrogen bond length, governs hydride NMR shifts in these molecules.
Area of Science:
- Quantum Chemistry
- Computational Chemistry
- Spectroscopy
Background:
- Atomic interactions dictate molecular structure and electron behavior.
- Electron delocalization and magnetic response are key to understanding chemical phenomena.
- Magnetically Induced Current Density (MICD) provides spatially-resolved electronic insights.
Purpose of the Study:
- To analyze the effect of relativistic spin-orbit (SO) coupling on MICD in heavy-atom hydrides.
- To investigate the relationship between SO effects, molecular geometry, MICD topology, and NMR shielding.
- To determine the primary factors influencing hydride NMR shifts in HMX molecules.
Main Methods:
- Four-component Dirac-Kohn-Sham calculations.
- Analysis of MICD strength and topology.
- Correlation with molecular geometry and 1H NMR shielding.
Main Results:
- SO coupling significantly alters MICD strength and topology in heavy-atom hydrides.
- SO effects on MICD are more influential on hydride NMR shifts than M-H bond length variations.
- Localized paratropic MICD vortices appear at hydride positions with strong trans-ligand influence (TLI) ligands.
Conclusions:
- Electronic spin-orbit coupling is the dominant factor in determining hydride NMR shifts for HMX molecules.
- The previously proposed role of metal-hydrogen bond length variations is disproven.
- MICD analysis reveals localized electronic effects crucial for understanding NMR properties.
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