Other formats:
BibTeX
LaTeX
RIS
@article{1414596,
author = {Vícha, Jan and Komorovsky, Stanislav and Repisky, Michal and Marek, Radek and Straka, Michal},
article_number = {6},
doi = {http://dx.doi.org/10.1021/acs.jctc.8b00144},
keywords = {nuclear magnetic resonance;NMR;chemical shift;spin-orbit coupling;shielding;perturbation theory},
language = {eng},
issn = {1549-9618},
journal = {Journal of Chemical Theory and Computation},
title = {Relativistic Spin-Orbit Heavy Atom on the Light Atom NMR Chemical Shifts: General Trends Across the Periodic Table Explained},
url = {http://dx.doi.org/10.1021/acs.jctc.8b00144},
volume = {14},
year = {2018}
}
TY - JOUR
ID - 1414596
AU - Vícha, Jan - Komorovsky, Stanislav - Repisky, Michal - Marek, Radek - Straka, Michal
PY - 2018
TI - Relativistic Spin-Orbit Heavy Atom on the Light Atom NMR Chemical Shifts: General Trends Across the Periodic Table Explained
JF - Journal of Chemical Theory and Computation
VL - 14
IS - 6
SP - 3025-3039
EP - 3025-3039
PB - American Chemical Society
SN - 15499618
KW - nuclear magnetic resonance;NMR;chemical shift;spin-orbit coupling;shielding;perturbation theory
UR - http://dx.doi.org/10.1021/acs.jctc.8b00144
L2 - http://dx.doi.org/10.1021/acs.jctc.8b00144
N2 - The importance of relativistic effects on the NMR parameters in heavy-atom (HA) compounds, particularly the SO-HALA (Spin-Orbit Heavy Atom on the Light Atom) effect on NMR chemical shifts, has been known for about 40 years. Yet, a general correlation between the electronic-structure and SO-HALA effect have been missing. By analyzing 1H NMR chemical shifts of the 6th-period hydrides (Cs-At) we discovered general electronic-structure principles and mechanisms that dictate the size and sign of the SO-HALA NMR chemical shifts. In brief, partially occupied HA valence shells induce relativistic shielding at the light atom (LA) nuclei, while empty HA valence shells induce relativistic deshielding. In particular, the LA nucleus is relativistically shielded in 5d2-5d8 and 6p4 HA hydrides and deshielded in 4f0, 5d0, 6s0, 6p0 HA hydrides. This general and intuitive concept explains periodic trends in the 1H NMR chemical shifts along the 6th-period hydrides (Cs-At) studied in this work. We present substantial evidence that the introduced principles have a general validity across the periodic table and can be extended to non-hydride LAs. The decades-old question why compounds with occupied frontier pi molecular orbitals (MOs) cause SO-HALA shielding at the LA nuclei, while the frontier sigma MOs cause deshielding is answered. We further derive connection between the SO-HALA NMR chemical shifts and Spin-Orbit-induced Electron Deformation Density (SO-EDD), a property, which can be obtained easily from differential electron densities and can be represented graphically. SO-EDD provides an intuitive understanding of the SO-HALA effect in terms of the depletion/concentration of the electron density at LA nuclei caused by spin-orbit coupling due to HA in the presence of magnetic field. Using an analogy between SO-EDD concept and arguments from classic NMR theory, the complex question of the SO-HALA NMR chemical shifts becomes easily understandable for a wide chemical audience.
ER -
VÍCHA, Jan, Stanislav KOMOROVSKY, Michal REPISKY, Radek MAREK and Michal STRAKA. Relativistic Spin-Orbit Heavy Atom on the Light Atom NMR Chemical Shifts: General Trends Across the Periodic Table Explained. \textit{Journal of Chemical Theory and Computation}. American Chemical Society, 2018, vol.~14, No~6, p.~3025-3039. ISSN~1549-9618. Available from: https://dx.doi.org/10.1021/acs.jctc.8b00144.
|
