Modulation of the Bonding between Copper and a Redox-Active Ligand by Hydrogen Bonds and Its Effect on Electronic Coupling and Spin States

Dolores L Ross; Andrew J Jasniewski; Joseph W Ziller; Emile L Bominaar; Michael P Hendrich; A S Borovik

doi:10.1021/jacs.3c09983

Modulation of the Bonding between Copper and a Redox-Active Ligand by Hydrogen Bonds and Its Effect on Electronic Coupling and Spin States

J Am Chem Soc. 2024 Jan 10;146(1):500-513. doi: 10.1021/jacs.3c09983. Epub 2023 Dec 27.

Authors

Dolores L Ross¹, Andrew J Jasniewski², Joseph W Ziller¹, Emile L Bominaar³, Michael P Hendrich³, A S Borovik¹

Affiliations

¹ Department of Chemistry, 1102 Natural Science II, University of California, Irvine, California 92697, United States.
² Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States.
³ Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.

PMID: 38150413
DOI: 10.1021/jacs.3c09983

Abstract

The exchange coupling of electron spins can strongly influence the properties of chemical species. The regulation of this type of electronic coupling has been explored within complexes that have multiple metal ions but to a lesser extent in complexes that pair a redox-active ligand with a single metal ion. To bridge this gap, we investigated the interplay among the structural and magnetic properties of mononuclear Cu complexes and exchange coupling between a Cu center and a redox-active ligand over three oxidation states. The computational analysis of the structural properties established a relationship between the complexes' magnetic properties and a bonding interaction involving a d_x2-y2 orbital of the Cu ion and π orbital of the redox-active ligand that are close in energy. The additional bonding interaction affects the geometry around the Cu center and was found to be influenced by intramolecular H-bonds introduced by the external ligands. The ability to synthetically tune the d-π interactions using H-bonds illustrates a new type of control over the structural and magnetic properties of metal complexes.