Zapata-Escobar, A.D.; Maldonado, A.F.; Mendoza-Cortes, J.L.; Aucar, G.A. NMR Magnetic Shielding in Transition Metal Compounds Containing Cadmium, Platinum, and Mercury. Magnetochemistry2023, 9, 165.
Zapata-Escobar, A.D.; Maldonado, A.F.; Mendoza-Cortes, J.L.; Aucar, G.A. NMR Magnetic Shielding in Transition Metal Compounds Containing Cadmium, Platinum, and Mercury. Magnetochemistry 2023, 9, 165.
Zapata-Escobar, A.D.; Maldonado, A.F.; Mendoza-Cortes, J.L.; Aucar, G.A. NMR Magnetic Shielding in Transition Metal Compounds Containing Cadmium, Platinum, and Mercury. Magnetochemistry2023, 9, 165.
Zapata-Escobar, A.D.; Maldonado, A.F.; Mendoza-Cortes, J.L.; Aucar, G.A. NMR Magnetic Shielding in Transition Metal Compounds Containing Cadmium, Platinum, and Mercury. Magnetochemistry 2023, 9, 165.
Abstract
In this article, we delve into the intricate behavior of electronic mechanisms underlying
NMR magnetic shieldings, σ, in molecules containing heavy atoms such as cadmium, platinum,
and mercury. Specifically, we explore PtXn^{−2} (X = F, Cl, Br, I; n = 4, 6) and XCl2 Te2 Y2 H6 (X = Cd,
Hg; Y = N, P) molecular systems. It is known that the leading electronic mechanisms responsible
for the relativistic effects on σ are well characterized by the linear response with elimination of
small components model (LRESC). In this study, we present results obtained from the innovative
LRESC-Loc model, which offers the same outcomes as the LRESC model but employs localized
molecular orbitals (LMOs) instead of canonical MOs. These LMOs provide a chemist’s representation
of atomic core, lone pairs, and bonds. The whole set of electronic mechanisms responsible of the
relativistic effects can be expressed in terms of both non-ligand-dependent and ligand-dependent
contributions. We elucidate the electronic origins of trends and behaviors exhibited by these di-
verse mechanisms in the aforementioned molecular systems. In PtX4^{−2} molecules, the predominant
relativistic mechanism is the well-established one-body spin-orbit (σ^SO(1) ) mechanism, while the
paramagnetic mass-velocity (σ^Mv ) and Darwin (σ^Dw ) contributing mechanisms also demand con-
sideration. However, in PtX6−2 molecules, the σ Mv+ Dw contribution surpasses that of the SO(1)
mechanism, thus influencing the overall ligand-dependent contributions. As for complexes con-
taining Cd and Hg, the ligand-dependent contributions exhibit similar magnitudes when nitrogen
is substituted with phosphorus. The only discrepancy arises from the σ^SO(1) contribution, which
changes sign between the two molecules due to the contribution of bond orbitals between the metal
and tellurium atoms.
Keywords
Analysis of magnetic shieldings; electronic mechanisms; LRESC-Loc; Ligand-dependent
Subject
Chemistry and Materials Science, Theoretical Chemistry
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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