Mechanisms of Ligand Hyperfine Coupling in Transition-Metal
Complexes: σ and π Transmission Pathways

J 2024

Mechanisms of Ligand Hyperfine Coupling in Transition-Metal Complexes: σ and π Transmission Pathways

NOVOTNÝ, Jan, Markéta MUNZAROVÁ and Radek MAREK

Basic information

Original name

Mechanisms of Ligand Hyperfine Coupling in Transition-Metal Complexes: σ and π Transmission Pathways

Authors

NOVOTNÝ, Jan (203 Czech Republic, belonging to the institution), Markéta MUNZAROVÁ (203 Czech Republic, belonging to the institution) and Radek MAREK (203 Czech Republic, guarantor, belonging to the institution)

Edition

Inorganic Chemistry, American Chemical Society, 2024, 0020-1669

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

10400 1.4 Chemical sciences

Country of publisher

United States of America

Confidentiality degree

není předmětem státního či obchodního tajemství

References:

DOI: 10.1021/acs.inorgchem.3c04425

Impact factor

Impact factor: 4.600 in 2022

Organization unit

Faculty of Science

DOI

http://dx.doi.org/10.1021/acs.inorgchem.3c04425

UT WoS

001227850700001

Keywords in English

EPR;pNMR;hyperfine interaction;Fermi contact;pi-conjugation;sigma-hyperconjugation

Abstract

V originále

Theoretical interpretation of hyperfine interactions was pioneered in the 1950s-1960s by the seminal works of McConnell, Karplus, and others for organic radicals and by Watson and Freeman for transition-metal (TM) complexes. In this work, we investigate a series of octahedral Ru(III) complexes with aromatic ligands to understand the mechanism of transmission of the spin density from the d-orbital of the metal to the s-orbitals of the ligand atoms. Spin densities and spin populations underlying ligand hyperfine couplings are analyzed in terms of pi-conjugative or sigma-hyperconjugative delocalization vs. spin polarization based on symmetry considerations and restricted open-shell vs. unrestricted wave function analysis. The transmission of spin density is shown to be most efficient in the case of symmetry-allowed pi-conjugative delocalization, but when the pi-conjugation is partially or fully symmetry-forbidden, it can be surpassed by the sigma-hyperconjugative delocalization. Despite a lower spin population of the ligand in sigma-hyperconjugative transmission, the hyperfine couplings can be larger because of the direct involvement of the ligand s-orbitals in this delocalization pathway. We demonstrate a quantitative correlation between the hyperfine couplings of aromatic ligand atoms and the characteristics of the metal-ligand bond modulated by the trans substituent, a hyperfine trans effect.

Links

GA21-06991S, research and development project

Name: Relativistické efekty v paramagnetické NMR spektroskopii (Acronym: RELMAG)

Investor: Czech Science Foundation, Relativistic Effects in Paramagnetic NMR Spectroscopy

90140, large research infrastructures

Name: e-INFRA CZ

Files attached

IC24_63_8580_acs.inorgchem.3c04424.pdf

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Citovat

NOVOTNÝ, Jan, Markéta MUNZAROVÁ and Radek MAREK. Mechanisms of Ligand Hyperfine Coupling in Transition-Metal Complexes: σ and π Transmission Pathways. Inorganic Chemistry. American Chemical Society, 2024, vol. 63, No 19, p. 8580-8592. ISSN 0020-1669. Available from: https://dx.doi.org/10.1021/acs.inorgchem.3c04425.

@article{2399546,
   author = {Novotný, Jan and Munzarová, Markéta and Marek, Radek},
   article_number = {19},
   doi = {http://dx.doi.org/10.1021/acs.inorgchem.3c04425},
   keywords = {EPR;pNMR;hyperfine interaction;Fermi contact;pi-conjugation;sigma-hyperconjugation},
   language = {eng},
   issn = {0020-1669},
   journal = {Inorganic Chemistry},
   title = {Mechanisms of Ligand Hyperfine Coupling in Transition-Metal Complexes: σ and π Transmission Pathways},
   url = {https://pubs.acs.org/doi/10.1021/acs.inorgchem.3c04425},
   volume = {63},
   year = {2024}
}

TY  - JOUR
ID  - 2399546
AU  - Novotný, Jan - Munzarová, Markéta - Marek, Radek
PY  - 2024
TI  - Mechanisms of Ligand Hyperfine Coupling in Transition-Metal Complexes: σ and π Transmission Pathways
JF  - Inorganic Chemistry
VL  - 63
IS  - 19
SP  - 8580-8592
EP  - 8580-8592
PB  - American Chemical Society
SN  - 00201669
KW  - EPR;pNMR;hyperfine interaction;Fermi contact;pi-conjugation;sigma-hyperconjugation
UR  - https://pubs.acs.org/doi/10.1021/acs.inorgchem.3c04425
N2  - Theoretical interpretation of hyperfine interactions was pioneered in the 1950s-1960s by the seminal works of McConnell, Karplus, and others for organic radicals and by Watson and Freeman for transition-metal (TM) complexes. In this work, we investigate a series of octahedral Ru(III) complexes with aromatic ligands to understand the mechanism of transmission of the spin density from the d-orbital of the metal to the s-orbitals of the ligand atoms. Spin densities and spin populations underlying ligand hyperfine couplings are analyzed in terms of pi-conjugative or sigma-hyperconjugative delocalization vs. spin polarization based on symmetry considerations and restricted open-shell vs. unrestricted wave function analysis. The transmission of spin density is shown to be most efficient in the case of symmetry-allowed pi-conjugative delocalization, but when the pi-conjugation is partially or fully symmetry-forbidden, it can be surpassed by the sigma-hyperconjugative delocalization. Despite a lower spin population of the ligand in sigma-hyperconjugative transmission, the hyperfine couplings can be larger because of the direct involvement of the ligand s-orbitals in this delocalization pathway. We demonstrate a quantitative correlation between the hyperfine couplings of aromatic ligand atoms and the characteristics of the metal-ligand bond modulated by the trans substituent, a hyperfine trans effect.
ER  -

NOVOTNÝ, Jan, Markéta MUNZAROVÁ and Radek MAREK. Mechanisms of Ligand Hyperfine Coupling in Transition-Metal Complexes: σ and π Transmission Pathways. \textit{Inorganic Chemistry}. American Chemical Society, 2024, vol.~63, No~19, p.~8580-8592. ISSN~0020-1669. Available from: https://dx.doi.org/10.1021/acs.inorgchem.3c04425.

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