Issue 44, 2022

Magnetically bistable cobalt-dioxolene complexes with a tetradentate N-donor base

Abstract

Synthesis and magnetic characterization of a family of cobalt-dioxolene complexes [(Me2TPA)Co(36-DBCat)] (1), [(Me2TPA)Co(36-DBCat)](PF6) (2) and [(Me2TPA)Co(diox-(OMe)3)](BPh4) (3) (Me2TPA = bis(6-methyl-2-pyridyl)methyl-(2-pyridylmethyl)amine; 36-DBCat = dianion of 3,6-di-tert-butylcatechol; diox-(OMe)3 – 2,5-di-tert-butyl-3,3,4-trimethoxy-6-oxocyclohexa-1,4-dienolate) is reported. The neutral complex 1 is found to form hexa- (CoO2N4, 1a) and pentacoordinated (CoO2N3, 1b) isomers. Variable temperature single crystal X-ray diffraction analysis of 1a and 1b clearly indicates the presence of the high-spin divalent metal ion and the dianionic catecholate form of the dioxolene ligand. Oxidation of 1 by ferrocenium hexafluorophosphate results in the formation of the ionic octahedral complex 2, demonstrating thermally induced valence-tautomeric transition (ls-CoIII-36-DBCat ⇄ hs-CoII-36-DBSQ) in the solid state with T1/2 = 175 K (36-DBSQ = radical-anionic semiquinonate form of the redox-ligand). In contrast, aerial oxidation of 1 is accompanied by changes in the structure of dioxolene resulting in oxocyclohexadienolate ligand and the formation of an ionic complex of high-spin divalent cobalt (3). Compounds 1a, 1b, and 3 are found to demonstrate a field-induced single-ion magnet behavior. The analysis of the electronic structures of 1, 2 and 3 with the aid of DFT and SA-CASSCF/NEVPT2 calculations is also given.

Graphical abstract: Magnetically bistable cobalt-dioxolene complexes with a tetradentate N-donor base

Supplementary files

Article information

Article type
Paper
Submitted
02 Sep 2022
Accepted
11 Oct 2022
First published
13 Oct 2022

Dalton Trans., 2022,51, 16876-16889

Magnetically bistable cobalt-dioxolene complexes with a tetradentate N-donor base

M. G. Chegerev, D. V. Korchagin, G. V. Shilov, N. N. Efimov, A. G. Starikov, A. V. Piskunov, A. V. Chernyshev, A. N. Bulgakov, V. I. Minkin, A. V. Palii and S. M. Aldoshin, Dalton Trans., 2022, 51, 16876 DOI: 10.1039/D2DT02874C

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