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Updated: Mar 3, 2026

Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
Acid-responsive rhenium(I) NHC complexes: pyrazine vs. pyridine
Pedro O Abate1,2,3,4, José Francisco Rizo1,2, Francisco José Fernández-de-Córdova2
1Departamento de Química Inorgánica, Universidad de Sevilla, C/Prof. García González 1, 41012 Seville, Spain. orivada@us.es.
Abstract:
Four rhenium(I) tricarbonyl complexes featuring pyridine- or pyrazine-functionalized N-heterocyclic carbenes were synthesized and fully characterized, including the determination of their molecular structures by single-crystal X-ray diffraction. Electrochemical and spectroelectrochemical measurements were performed. The development of isosteric Re(I) complexes enabled a direct comparison of how Brønsted and Lewis acids influence their electronic properties. Complexes containing the pyridyl core showed no detectable changes in either electrochemical or spectroscopic studies. In contrast, those bearing the pyrazine fragment exhibited significant shifts at both reductive and oxidative potentials, attributable to the extra nitrogen atom in the 1,4-diazine ring, which can interact with Brønsted (and Lewis) acids. In this regard, comparison of alkali salts with Brønsted acids revealed that the presence of the latter induces substantially larger electronic perturbations.
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