|
1
|
de Souza MS, Reis SG, Stinghen D, Escobar LBL, Allão Cassaro RA, Poneti G, S Bortolot C, Marbey J, Hill S, Vaz MGF. High-Frequency EPR Studies of New 2p-3d Complexes Based on a Triazolyl-Substituted Nitronyl Nitroxide Radical: The Role of Exchange Anisotropy in a Cu-Radical System. Inorg Chem 2022; 61:12118-12128. [PMID: 35876616 DOI: 10.1021/acs.inorgchem.2c00679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using the 1-(m-tolyl)-1H-1,2,3-triazole-4-(4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) (TlTrzNIT) radical and metal β-diketonate complexes [M(hfac)2(H2O)2], where hfac is hexafluoroacetylacetonato, three new 2p-3d heterospin complexes were synthesized. Their structures were solved using single crystal X-ray diffraction data, and magnetic investigation was performed by DC and AC measurements and multifrequency EPR spectroscopy. Compounds 1 and 2 are isostructural complexes with molecular formula [M3(TlTrzNIT)2(hfac)6] (MII = Mn or Cu) while compound 3 is the mononuclear [Co(TlTrzNIT)(hfac)2] complex. In all complexes, the radical acts as a bidentate ligand through the oxygen atom of the nitroxide moiety and the nitrogen atom from the triazole group. Furthermore, in compounds 1 and 2, the TlTrzNIT is bridge-coordinated between two metal centers, leading to the formation of trinuclear complexes. The fitting of the static magnetic behavior reveals antiferromagnetic and ferromagnetic intramolecular interactions for complexes 1 and 2, respectively. The EPR spectra of 1 are well described by an isolated ferrimagnetic S = 13/2 (= 5/2 - 1/2 + 5/2 - 1/2 + 5/2) ground state with a biaxial zero-field splitting (ZFS) interaction characterized, respectively, by 2nd order axial and rhombic parameters, D and E, such that E/D is close to the maximum of 0.33. Meanwhile, EPR spectra for 2 are explained in terms of a ferromagnetic model with weakly anisotropic Cu-radical exchange interactions, giving rise to an isolated S = 5/2 (= 5 × 1/2) ground state with both an anisotropic g tensor and a weak ZFS interaction. Complex 2 represents one of only a few examples of Cu-radical moieties with measurable exchange anisotropy.
Collapse
Affiliation(s)
- Mateus S de Souza
- Instituto de Química, Universidade Federal Fluminense, Niterói, Rio de Janeiro 24020-150, Brazil
| | - Samira G Reis
- Instituto de Química, Universidade Federal Fluminense, Niterói, Rio de Janeiro 24020-150, Brazil
| | - Danilo Stinghen
- Instituto de Química, Universidade Federal Fluminense, Niterói, Rio de Janeiro 24020-150, Brazil
| | - Lívia B L Escobar
- Instituto de Física, Universidade Federal Fluminense, Niterói, Rio de Janeiro 24210-346, Brazil.,NHMFL, Florida State University, Tallahassee, Florida 32310, United States.,Departamento de Química, Pontifícia Universidade Católica, Gávea, Rio de Janeiro, RJ 22453-900, Brazil
| | - Rafael A Allão Cassaro
- Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-909, Brazil
| | - Giordano Poneti
- Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-909, Brazil
| | - Carolina S Bortolot
- Instituto de Química, Universidade Federal Fluminense, Niterói, Rio de Janeiro 24020-150, Brazil
| | - Jonathan Marbey
- NHMFL, Florida State University, Tallahassee, Florida 32310, United States.,Department of Physics, Florida State University, Tallahassee, Florida 32306, United States
| | - Stephen Hill
- NHMFL, Florida State University, Tallahassee, Florida 32310, United States.,Department of Physics, Florida State University, Tallahassee, Florida 32306, United States
| | - Maria G F Vaz
- Instituto de Química, Universidade Federal Fluminense, Niterói, Rio de Janeiro 24020-150, Brazil
| |
Collapse
|