Probing the structure of copper(II)-casiopeina type coordination complexes [Cu(O-O)(N-N)]+ by EPR and ENDOR spectroscopy

Folli, Andrea ORCID: https://orcid.org/0000-0001-8913-6606, Ritterskamp, Nadine, Richards, Emma ORCID: https://orcid.org/0000-0001-6691-2377, Platts, James A. ORCID: https://orcid.org/0000-0002-1008-6595 and Murphy, Damien M. ORCID: https://orcid.org/0000-0002-5941-4879 2021. Probing the structure of copper(II)-casiopeina type coordination complexes [Cu(O-O)(N-N)]+ by EPR and ENDOR spectroscopy. Journal of Catalysis 394 , pp. 220-227. 10.1016/j.jcat.2020.07.016

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Abstract

Although copper based complexes have been widely used in homogeneous catalysis, more recently they are attracting considerable attention as pharmaceutical therapeutic agents. Of paramount importance in their efficacy of use is their structure and electronic properties, which can be thoroughly probed using advanced EPR techniques. In this study, a series of [Cu(acac)(N-N)]+ Casiopeina type complexes were investigated, bearing a series of diimine N-N ligands (including bipy, phen, Py-bipy and dppz). All complexes displayed rhombic g and CuA tensors, although the extent of rhombicity was dependent on the N-N ligand. Greater Cu(II)-N2 in-plane distortion, away from the square planar arrangement, was detected by CW W-band EPR for the smaller bipy and phen ligands compared to the larger Py-bipy and dppz ligands. Changes in ligand spin density distributions (over the 1H and 14N nuclei) were revealed by CW Q-band ENDOR. The largest components of the 1H imine and 14N hyperfine coupling decreased as the ligand size increased, following the trend bipy > phen > Py-bipy > dppz. These results indicate how even small structural and electronic (spin density) perturbations within the Casiopeina family of Cu(II) complexes can be probed by advanced EPR methods.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Publisher:	Elsevier
ISSN:	0021-9517
Funders:	EPSRC
Date of First Compliant Deposit:	18 August 2020
Date of Acceptance:	17 July 2020
Last Modified:	16 Oct 2024 10:20
URI:	https://orca.cardiff.ac.uk/id/eprint/134274

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