Valence tautomerism in a cobalt-dioxolene complex containing an imidazolic ancillary ligand.

Autor: Moledo Vicente Guedes A; Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil giordano.poneti@unitus.it., Sodré de Abreu L; Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil giordano.poneti@unitus.it., Maldonado IAV; Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil giordano.poneti@unitus.it., Fernandes WS; Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil giordano.poneti@unitus.it., Cardozo TM; Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil giordano.poneti@unitus.it., A Allão Cassaro R; Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil giordano.poneti@unitus.it., Scarpellini M; Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil giordano.poneti@unitus.it., Poneti G; Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil giordano.poneti@unitus.it.
Jazyk: angličtina
Zdroj: RSC advances [RSC Adv] 2023 Jul 04; Vol. 13 (29), pp. 20050-20057. Date of Electronic Publication: 2023 Jul 04 (Print Publication: 2023).
DOI: 10.1039/d3ra03235c
Abstrakt: This work reports the synthesis, structural, spectroscopic and magnetic investigation of two complexes, [Co(bmimapy)(3,5-DTBCat)]PF 6 ·H 2 O (1) and [Co(bmimapy)(TCCat)]PF 6 ·H 2 O (2), where bmimapy is an imidazolic tetradentate ancillary ligand and 3,5-DTBCat and TCCat are the 3,5-di- tert -butyl-catecholate and tetrachlorocatecholate anions, respectively. Their structures have been elucidated using single crystal X-ray diffraction, showing a pseudo-octahedral cobalt ion bound to a chelating dioxolene ligand and the ancillary bmimapy ligand in a folded conformation. Magnetometry displayed an entropy-driven, incomplete, Valence Tautomeric (VT) process for 1 in the 300-380 K temperature range, while 2 displayed a temperature independent, diamagnetic low-spin cobalt(iii)-catecholate charge distribution. This behaviour was interpreted on the basis of the cyclic voltammetric analysis, allowing the estimation of the free energy difference associated with the VT interconversion of +8 and +96 kJ mol -1 for 1 and 2, respectively. A DFT analysis of this free energy difference highlighted the ability of the methyl-imidazole pendant arm of bmimapy favouring the onset of the VT phenomenon. This work introduces the imidazolic bmimapy ligand to the scientific community working in the field of valence tautomerism, increasing the library of ancillary ligands to prepare temperature switchable molecular magnetic materials.
Competing Interests: There are no conflicts of interest to declare.
(This journal is © The Royal Society of Chemistry.)
Databáze: MEDLINE
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