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Titre: 1,4-Dimethoxybutadienediyl-Bridged diiron compounds in three oxidation states : evaluation of delocalization effects
Auteur(s): Sahnoune, Hiba
Mahias, Virginie
Halet, Jean-François
Lapinte, Claude
Mots-clés: Chemical bonds
Cyclic voltammetry
Electron spin resonance spectroscopy
Isomers
Mass spectrometry
Near infrared spectroscopy
Nuclear magnetic resonance spectroscopy
Oxidation
Quantum chemistry
Date de publication: 2019
Editeur: American Chemical Society
Collection/Numéro: Organometallics/ Vol.38, N°14 (2019);pp. 2724–2737
Résumé: The binuclear iron complexes [Cp∗(PMe3)(CO)Fe-C(OCH3)=CH-CH=C(OCH3)-Fe(PMe3)(CO)Cp∗] (1meso and 1dl) were prepared by double deprotonation of their known parents [Cp∗(PMe3)(CO)Fe=C(OCH3)CH2-CH2-C(OCH3)=Fe(PMe3)(CO)Cp∗](PF6)2 (5meso and 5dl) and were isolated in good yield (90%). These complexes were characterized by ESI-mass spectrometry, IR and multinuclear NMR spectroscopy, and cyclic voltammetry. The singly and doubly oxidized forms 1meso(PF6)n and 1dl(PF6)n (n = 1, 2) were prepared by oxidation of the parent neutral complexes with 1 and 2 equiv of ferrocenium salt (93-100% yield). The related complex [Cp∗(dppe)Fe-C(OCH3)=CH-CH=C(OCH3)-Fe(dppe)Cp∗](PF6) (2(PF6)) was obtained by reduction of the known dicationic derivative [Cp∗(dppe)Fe-C(OCH3)=CH-CH=C(OCH3)-Fe(dppe)Cp∗](PF6) (2(PF6)2) with 1 equiv of cobaltocene (100% yield). Multinuclear NMR spectroscopy allowed us to establish the diiron(II) conjugated μ-bis(carbene) structure for 1meso(PF6)2 and 1dl(PF6)2. In the case of the meso derivative, 1H NMR revealed the presence of E and Z isomers in a 4:1 ratio, confirming the presence of a C=C double bond in the middle of the bridge. The three radicals 1meso(PF6), 1dl(PF6), and 2(PF6), which are thermally stable, were analyzed by IR, Mössbauer, ESR, UV-vis, and NIR spectroscopy. Experimental data, discussed with the support of quantum chemistry calculations performed at the DFT level of theory, indicate that these radical cations exhibit characteristics of oxidation on the butadienediyl bridge rather than on the metal centers
URI/URL: https://pubs.acs.org/doi/10.1021/acs.organomet.9b00174
https://doi.org/10.1021/acs.organomet.9b00174
http://dlibrary.univ-boumerdes.dz:8080/handle/123456789/6747
ISSN: 02767333
1520-6041 Electronic
Collection(s) :Publications Internationales

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