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dc.contributor.authorBora, Pankaj L
dc.contributor.authorNovotny, Jan
dc.contributor.authorRuud, Kenneth
dc.contributor.authorKomorovsky, Stanislav
dc.contributor.authorMarek, Radek
dc.date.accessioned2020-03-30T13:13:03Z
dc.date.available2020-03-30T13:13:03Z
dc.date.issued2018-11-28
dc.description.abstractElectron and nuclear magnetic resonance spectroscopies are indispensable and powerful methods for investigating the molecular and electronic structures of open-shell systems. We demonstrate that the NMR and EPR parameters are extremely sensitive quantitative probes for the electronic spin density around heavy-metal atoms and the metal–ligand bonding. Using relativistic density-functional theory, we have analyzed the relation between the spin density and the EPR and NMR parameters in paramagnetic iridium(II/IV) complexes with a PNP pincer ligand. As the magnetic-response parameters for compounds containing 5d transition metal(s) are heavily affected by spin–orbit coupling, relativistic effects must be included in the calculations. We have used a recent implementation of the fully relativistic Dirac−Kohn–Sham (DKS) method employing the hybrid PBE0 functional and an implicit solvent model to calculate EPR parameters and hyperfine NMR shifts. The modulation of the metal–ligand bond by the trans substituent (−Cl or ≡N) and the electronic spin structure around the central metal atom and ligands are shown to be reflected in the “long-range” through-bond Fermi-contact (FC) contributions to the ligand 13C and 1H hyperfine couplings. Interestingly, the hyperfine coupling constant of the ligand atom L (AL) bonded directly to the iridium center changes its sign because of the dominating role of the paramagnetic spin–orbit (PSO) term. Furthermore, the electronic g-shift and the PSO contribution to the ligand AL are shown to invert their signs when nitrogen is substituted for chlorine, reflecting the different formal metal oxidation states and the change in metal–ligand bond character. A full understanding of the substituent effects is provided by using chemical bond concepts in combination with a molecular-orbital (MO) theory analysis of the second-order perturbation theory expression for the EPR parameters. Our findings are easily transferable to other systems containing d-block elements and beyond. Relativistic DFT calculations of magnetic-resonance parameters are expected to frequently assist in future experimental observations and the characterization of hitherto unknown unstable or exotic species.en_US
dc.descriptionReprinted with permission from Bora PL, Novotny J, Ruud K, Komorovsky S, Marek R. Electron-Spin Structure and Metal-Ligand Bonding in Open-Shell Systems from Relativistic EPR and NMR: A Case Study of Square-Planar Iridium Catalysts. Journal of Chemical Theory and Computation. 2019;15(1):201-214. Copyright © 2018 American Chemical Societyen_US
dc.identifier.citationBora PL, Novotny J, Ruud K, Komorovsky S, Marek R. Electron-Spin Structure and Metal-Ligand Bonding in Open-Shell Systems from Relativistic EPR and NMR: A Case Study of Square-Planar Iridium Catalysts. Journal of Chemical Theory and Computation. 2019;15(1):201-214en_US
dc.identifier.cristinIDFRIDAID 1695125
dc.identifier.doi10.1021/acs.jctc.8b00914
dc.identifier.issn1549-9618
dc.identifier.issn1549-9626
dc.identifier.urihttps://hdl.handle.net/10037/17918
dc.language.isoengen_US
dc.publisherAmerican Chemical Societyen_US
dc.relation.journalJournal of Chemical Theory and Computation
dc.relation.projectIDNorges forskningsråd: 262695en_US
dc.relation.projectIDinfo:eu-repo/grantAgreement/RCN/SFF/26295/Norway/Hylleraas Centre for Quantum Molecular Sciences//en_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright © 2018 American Chemical Societyen_US
dc.subjectVDP::Mathematics and natural science: 400::Chemistry: 440en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Kjemi: 440en_US
dc.titleElectron-Spin Structure and Metal-Ligand Bonding in Open-Shell Systems from Relativistic EPR and NMR: A Case Study of Square-Planar Iridium Catalystsen_US
dc.type.versionacceptedVersionen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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