Influence of the ligand-field on EPR parameters of cis- and trans-isomers in Mo systems relevant to molybdenum enzymes: Experimental and density functional theory study

DOI

10.1016/j.jinorgbio.2023.112228

Authors

Victor N. Nemykin, Department of Chemistry, University of Tennessee - Knoxville, Knoxville, TN 37996, USA; Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, MN 55812, USA. Electronic address: vnemykin@utk.edu.
Jared R. Sabin, Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, MN 55812, USA.
Brian W. Kail, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15216, USA.
Anup Upadhyay, Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
Michael P. Hendrich, Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA. Electronic address: hendrich@andrew.cmu.edu.
Partha Basu, Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15216, USA; Department of Chemistry and Chemical Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA. Electronic address: basup@iupui.edu.

Document Type

Journal Article

Publication Date

8-1-2023

Publication Title

Journal of inorganic biochemistry

Volume

245

First Page

112228

Keywords

DFT calculations, DMSO reductase, EPR spectroscopy, Molybdenum enzymes, Molybdenum hyperfine parameters

Abstract

The electron paramagnetic resonance (EPR) investigation of mononuclear cis- and trans-(L1O)MoOCl complexes [L1OH = bis(3,5-dimethylpyrazolyl)-3-tert-butyl-2-hydroxy-5-methylphenyl)methane] reveals a significant difference in their spin Hamiltonian parameters which reflect different equatorial and axial ligand fields created by the heteroscorpionate donor atoms. Density functional theory (DFT) was used to calculate the values of principal components and relative orientations of the g and A tensors, and the molecular framework in four pairs of isomeric mononuclear oxo‑molybdenum(V) complexes (cis- and trans-(L1O)MoOCl, cis,cis- and cis,trans-(L-NS)MoOCl [L-NSH = N,N'-dimethyl-N,N'-bis(mercaptophenyl)ethylenediamine], cis,cis- and cis,trans-(L-NS)MoO(SCN), and cis- and trans-[(dt)MoO(OMe)] [dtH = 2,3-dimercapto-2-butene]). Scalar relativistic DFT calculations were conducted using three different exchange-correlation functionals. It was found that the use of hybrid exchange-correlation functional with 25% of the Hartree-Fock exchange leads to the best quantitative agreement between theory and experiment. A simplified ligand-field approach was used to analyze the influence of the ligand fields in all cis- and trans-isomers on energies and contributions of molybdenum d-orbital manifold to g and A tensors and relative orientations. Specifically, contributions that originated from the spin-orbit coupling of the d, d, and d orbitals into the ground state have been discussed. The new findings are discussed in the context of the experimental data of mononuclear molybdoenzyme, DMSO reductase.

Open Access

37149488 (pubmed); NIHMS1896489 (mid); PMC10330323 (pmc); 10.1016/j.jinorgbio.2023.112228 (doi); S0162-0134(23)00110-1 (pii)

Preprint

Link to Free Full Text

Repository Citation

Nemykin, V. N., Sabin, J. R., Kail, B. W., Upadhyay, A., Hendrich, M. P., & Basu, P. (2023). Influence of the ligand-field on EPR parameters of cis- and trans-isomers in Mo systems relevant to molybdenum enzymes: Experimental and density functional theory study. Journal of inorganic biochemistry, 245, 112228. https://doi.org/10.1016/j.jinorgbio.2023.112228