Browsing by Author "Lapinte, Claude"

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    1,4-Dimethoxybutadienediyl-Bridged diiron compounds in three oxidation states : evaluation of delocalization effects
    (American Chemical Society, 2019) Sahnoune, Hiba; Mahias, Virginie; Halet, Jean-François; Lapinte, Claude
    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
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    Localized Class-II Mixed Valency in Zwitterionic Diiron Complexes Containing [Cp*(dppe)Fe]n+Units and an Internal Carboxylate: Experimental Validation and Theoretical Insights into Solvent-Stabilized Charge Trapping
    (American Chemical Society, 2025) Sahnoune, Hiba; Lepont, Joseph; Lapinte, Claude; Hamon, Jean-René; Halet, Jean-François
    Zwitterionic mixed-valence (MV) complexes offer a compelling strategy for designing charge-neutral molecular components for quantum-dot cellular automata (QCA). In this work, organometallic zwitterions 1a and 1b featuring two [Cp*(dppe)Fe] redox centers linked by a meta-phenylene ethynylene bridge and an internal carboxylate were generated and characterized. A comprehensive investigation combining cyclic voltammetry, IR, and vis–NIR spectroscopies unambiguously establishes that both 1a and 1b behave as charge-localized Robin–Day class-II MV systems. This crucial finding demonstrates that the covalently tethered counterion does not significantly alter the weak electronic communication inherent to the meta-substituted bridge. To rationalize these experimental results, density functional theory (DFT) calculations were performed. It is shown that while simplified gas-phase models inadequately predict a delocalized state, calculations incorporating a polarizable continuum model (PCM–CH2Cl2) successfully reproduce the experimentally observed charge localization. The agreement between the experimental data and the solvated theoretical model provides robust validation for the class-II description and confirms this zwitterionic design as a viable approach for creating charge-neutral molecular wires
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    Redox properties of ferrocenyl Ene-diynyl-Bridged Cp*(dppe)M–C≡C–1,4-(C6H4) complexes
    (American Chemical Society, 2018) Makhoul, Rim; Gluyas, Josef B. G.; Vincent, Kevin B.; Sahnoune, Hiba; Halet, Jean-François; Low, Paul J.; Hamon, Jean-René; Lapinte, Claude