University of Oulu

Rouf, S., Mareš, J., Vaara, J. (2017) Relativistic Approximations to Paramagnetic NMR Chemical Shift and Shielding Anisotropy in Transition Metal Systems. Journal of Chemical Theory and Computation, 13 (8), 3731-3745. doi:10.1021/acs.jctc.7b00168

Relativistic approximations to paramagnetic NMR chemical shift and shielding anisotropy in transition metal systems

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Author: Rouf, Syed Awais1; Mareš, Jiří1; Vaara, Juha1
Organizations: 1NMR Research Unit, University of Oulu, P.O. Box 3000, Oulu FIN-90014, Finland
Format: article
Version: published version
Access: embargoed
Persistent link: http://urn.fi/urn:nbn:fi-fe201801031039
Language: English
Published: American Chemical Society, 2017
Publish Date: 2018-06-21
Description:

Abstract

We apply approximate relativistic methods to calculate the magnetic property tensors, i.e., the g-tensor, zero-field splitting (ZFS) tensor (D), and hyperfine coupling (HFC) tensors, for the purpose of constructing paramagnetic nuclear magnetic resonance (pNMR) shielding tensors. The chemical shift and shielding anisotropy are calculated by applying a modern implementation of the classic Kurland–McGarvey theory ( J. Magn. Reson. 1970, 2, 286), which formulates the shielding tensor in terms of the g- and HFC tensors obtained for the ground multiplet, in the case of higher than doublet multiplicity defined by the ZFS interaction. The g- and ZFS tensors are calculated by ab initio complete active space self-consistent field and N-electron valence-state perturbation theory methods with spin–orbit (SO) effects treated via quasidegenerate perturbation theory. Results obtained with the scalar relativistic (SR) Douglas–Kroll–Hess Hamiltonian used for the g- and ZFS tensor calculations are compared with nonrelativistically based computations. The HFC tensors computed using the fully relativistic four-component matrix Dirac–Kohn–Sham approach are contrasted against perturbationally SO-corrected nonrelativistic results in the density functional theory framework. These approximations are applied on paramagnetic metallocenes (MCp₂) (M = Ni, Cr, V, Mn, Co, Rh, Ir), a Co(II) pyrazolylborate complex, and a Cr(III) complex. SR effects are found to be small for g and D in these systems. The HFCs are found to be more influenced by relativistic effects for the 3d systems. However, for some of the 3d complexes, nonrelativistic calculations give a reasonable agreement with the experimental chemical shift and shielding anisotropy. The influence of scalar relativity is strong for the 5d IrCp₂ system. This mixed ab initio/DFT technique, with a fully relativistic method used for the critical HFC tensor, should be useful for the treatment of both electron correlation and relativistic effects at a reasonable computational cost to compute the pNMR shielding tensors in transition metal systems.

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Series: Journal of chemical theory and computation
ISSN: 1549-9618
ISSN-E: 1549-9626
ISSN-L: 1549-9618
Volume: 13
Issue: 8
Pages: 3731 - 3745
DOI: 10.1021/acs.jctc.7b00168
OADOI: https://oadoi.org/10.1021/acs.jctc.7b00168
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
Subjects:
Funding: The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme FP7/2007-2013 under REA grant agreement no. 317127. The work of J.V. and J.M. was additionally supported by the Academy of Finland projects 258565 and 296292. J.M. acknowledges a personal grant from Finnish Cultural Foundation.
EU Grant Number: (317127) PNMR - Pushing the Envelope of Nuclear Magnetic Resonance Spectroscopy for Paramagnetic Systems. A Combined Experimental and Theoretical Approach
Academy of Finland Grant Number: 258565
296292
Detailed Information: 258565 (Academy of Finland Funding decision)
296292 (Academy of Finland Funding decision)
Copyright information: © 2017 American Chemical Society.