Doubly phenoxide-bridged binuclear copper(II) complexes with ono tridentate schiff base ligand: Synthesis, structural, magnetic and theoretical studies

International audienceThe tridentate ONO-donor Schiff base ligand H2L, derived from the condensation of 1-anisyl-1,3-butanedione and 2-aminophenol, was generated in situ and reacted with Cu(NO3)2*3H2O to yield two doubly phenoxo bridged di-copper(II) complexes depending on the nitrogenous base used. [Cu2L2] (1) is obtained in 85% and 75% yield in the presence of pyridine or 4-picoline, respectively, and [(py-tBu)2Cu2L2] (2) is isolated in 75% yield in the presence of 4-tert-butylpyridine. Compounds 1 and 2 were characterized in the solid-state by elemental analysis and FT-IR spectroscopy. Single crystal X-ray diffraction study reveals that in 1 the two four-coordinated copper atoms adopt a square planar geometry, whereas in 2 each Cu(II) metal ion shows a five coordinate square pyramidal (ONO,N + O) geometry. In each dimer, two μ-phenolic oxygen atoms bridge the two half-units forming a planar Cu2O2 core. EPR studies in fluid solutions indicate that the dimeric structure of 1 and 2 is destroyed upon dissolution. In the solid-state, 1 is EPR silent, whereas 2 presents an unresolved broad resonance (ΔH peak-to-peak = 71.5 G) with g = 2.071 at 298 K, along with the triplet state (S = 1) signature at g = 4.181. Variable temperature (2-300 K) magnetic susceptibility measurements exhibit strong antiferromagnetic interactions between the Cu(II) centers with a J value of −397 cm−1 for 1, while no interaction operates between the two spins localized on Cu(II) metal ions in 2. Ab initio calculations were also performed to supplement the experimental results

Binuclear organoiron redox complexes with a functionnal bridge for molecular electronics

Ce manuscrit de thèse décrit la conception, l’élaboration et l’étude de complexes organofers électro-actifs dans lesquels deux unités terminales Cp*(dppe)FeII/III sont reliés par un pont fonctionnel. Dans le premier chapitre, nous avons présenté une réaction à la fois originale et efficace catalysée par le Pd(0) qui permet d’accèder à la [5,5’-{(Cp*(dppe)Fe–C≡C}2-(μ-2,2’-bipy)]. Le deuxième chapitre porte sur la présentation d’une voie de synthèse rapide et efficace du métallo-ligand [6,6’-{Cp*(dppe)Fe–C≡C}2-(μ-2,2’-bipy)]. Le troisième chapitre de ce mémoire est consacré à l’utilisation du ligand 1’,1’’’-bis(éthynyle)biferrocényle comme pont entre deux terminaisons électroactives Cp*(dppe)FeII/III. L’espaceur électro-actif joue le rôle de relais moléculaire favorisant le transfert électronique d’une terminaison à l’autre par sauts successifs. Afin d’ajuster les potentiels redox des terminaisons par rapport à ceux du biferrocényle, les terminaisons Cp(PPh3)2M (M = Ru, Os) ont également été utilisées pour substituer un ou deux sites organofers. Le chapitre quatre est dédié aux travaux réalisés sur le système hybride Cp*(dppe)Fe-C≡C-TTMe3. Dans cette molécule, le site Cp*(dppe)FeII/III interagit à travers le pont acétylure avec le fragment tétrathiafulvalényle. La nouvelle molécule est stable sous trois degrés d’oxydation. L’espèce monocationique se comporte comme un composé à valence mixte de classe II et le couplage électronique entre les deux électrophores a été déterminé (Hab = 320 cm-1). Dans le cinquième et dernier chapitre nous mettrons à profit la découverte d’une réaction d’activation de la liaison C-H du groupement méthyle situé sur le même cycle du TTF et de l’acétylure de fer dans le composé [Cp*(dppe)Fe-C≡C-TTMe3](PF6)3. Cette réaction permet la synthèse du complexe moléculaire multifonctionnel [Cp*(dppe)Fe=C=C=TTFMe2=CH-CH=TTFMe2=C=C=Fe(dppe)Cp*][PF6]2 avec de très bon rendement. Les propriétés physicochimiques de ce nouveau complexe analysées avec le support de la chimie quantique permettent de révéler les caractéristiques originales de ce composé inédit.This thesis highlights the conception, synthesis and studies of redox-active organoiron complexes in which the two termini Cp*(dppe)FeII/III are linked by a functional bridge. In chapter I, an original and efficient synthetic Pd(0) catalysed homocoupling procedure is reported involving mononuclear organoiron(II) intermediates allowing us to isolate [5,5’-{Cp*(dppe)Fe–C≡C}2-(μ-2,2’-bipy)]. In chapter II, a rapid and efficient synthetic access to the redox-active metallo-ligand [6,6’-{cp*(dppe)Fe–C≡C}2-(μ-2,2’-bipy)] is described. In chapter III, the synthesis and properties of a series of complexes containing bis(ethynyl)biferrocene as a bridge between different redoxactive groups is pointed out. The redox bridge acts as a molecular relay for the electronic exchange between the termini via an electron hopping pathway. In order to tune the redox potential compared with those of biferrocene, one or two organoiron groups have been substituted by the Cp(PPh3)2M (M = Ru, Os) groups. In chapter IV, works are dedicated to the hybrid system Cp*(dppe)Fe-C≡C-TTMe3. In this molecule, electronic interactions take place between the Cp*(dppe)FeII/III center and the tetrathiafulvalene core through the ethynyl bridge. The new molecule is stable under three redox states. The mono-oxidized species behaves as a mixed valence species with an electronic coupling Hab = 320 cm-1 between the two electrophores. In the fifth and final chapter, the discovery of a CH bond activation of a methyl group located on the same cycle of the TTF core and the iron acetylide for the compound [Cp*(dppe)Fe-C≡C-TTMe3](PF6)3 is reported. This new reaction allows the synthesis of the multicomponent molecule [Cp*(dppe)Fe=C=C=TTFMe2=CH-CH=TTFMe2=C=C=Fe(dppe)Cp*][PF6]2 in good yield. The resulting device displays specific properties analysed with the support of the quantum chemistry

Épitaphe paléo-chrétienne d'Eaunes (Haute-Garonne)

Justaud Jacqueline. Épitaphe paléo-chrétienne d'Eaunes (Haute-Garonne). In: Pallas, 10/1961. pp. 91-95

Development of the Meyer Schuster Rearrangement on Propargylic Alcohols with Fluorinated Chains.

International audienceThe Meyer‐Schuster Rearrangement (MSR) is a challenging process for propargylic alcohols bearing fluorine atom(s) on their chains. Most classical reagents/catalysts failed to perform MSR but, after extensive screening, we demonstrated that phosphomolybdic acid was the first efficient catalyst with such derivatives. scope and limitations have been studied, affording fluorine‐containing enones as useful intermediates synthesis of targets fluorine(s) side It exemplified by preparation 2‐piperidino‐pyrimidine pyrazole

Complexes binucléaires organofers électro-actifs à pont fonctionnel pour l'électronique moléculaire

Ce manuscrit de thèse décrit la conception, l élaboration et l étude de complexes organofers électro-actifs dans lesquels deux unités terminales Cp*(dppe)FeII/III sont reliés par un pont fonctionnel. Dans le premier chapitre, nous avons présenté une réaction à la fois originale et efficace catalysée par le Pd(0) qui permet d accèder à la [5,5 -{(Cp*(dppe)Fe C C}2-( -2,2 -bipy)]. Le deuxième chapitre porte sur la présentation d une voie de synthèse rapide et efficace du métallo-ligand [6,6 -{Cp*(dppe)Fe C C}2-( -2,2 -bipy)]. Le troisième chapitre de ce mémoire est consacré à l utilisation du ligand 1 ,1 -bis(éthynyle)biferrocényle comme pont entre deux terminaisons électroactives Cp*(dppe)FeII/III. L espaceur électro-actif joue le rôle de relais moléculaire favorisant le transfert électronique d une terminaison à l autre par sauts successifs. Afin d ajuster les potentiels redox des terminaisons par rapport à ceux du biferrocényle, les terminaisons Cp(PPh3)2M (M = Ru, Os) ont également été utilisées pour substituer un ou deux sites organofers. Le chapitre quatre est dédié aux travaux réalisés sur le système hybride Cp*(dppe)Fe-C C-TTMe3. Dans cette molécule, le site Cp*(dppe)FeII/III interagit à travers le pont acétylure avec le fragment tétrathiafulvalényle. La nouvelle molécule est stable sous trois degrés d oxydation. L espèce monocationique se comporte comme un composé à valence mixte de classe II et le couplage électronique entre les deux électrophores a été déterminé (Hab = 320 cm-1). Dans le cinquième et dernier chapitre nous mettrons à profit la découverte d une réaction d activation de la liaison C-H du groupement méthyle situé sur le même cycle du TTF et de l acétylure de fer dans le composé [Cp*(dppe)Fe-C C-TTMe3](PF6)3. Cette réaction permet la synthèse du complexe moléculaire multifonctionnel [Cp*(dppe)Fe=C=C=TTFMe2=CH-CH=TTFMe2=C=C=Fe(dppe)Cp*][PF6]2 avec de très bon rendement. Les propriétés physicochimiques de ce nouveau complexe analysées avec le support de la chimie quantique permettent de révéler les caractéristiques originales de ce composé inédit.This thesis highlights the conception, synthesis and studies of redox-active organoiron complexes in which the two termini Cp*(dppe)FeII/III are linked by a functional bridge. In chapter I, an original and efficient synthetic Pd(0) catalysed homocoupling procedure is reported involving mononuclear organoiron(II) intermediates allowing us to isolate [5,5 -{Cp*(dppe)Fe C C}2-( -2,2 -bipy)]. In chapter II, a rapid and efficient synthetic access to the redox-active metallo-ligand [6,6 -{cp*(dppe)Fe C C}2-( -2,2 -bipy)] is described. In chapter III, the synthesis and properties of a series of complexes containing bis(ethynyl)biferrocene as a bridge between different redoxactive groups is pointed out. The redox bridge acts as a molecular relay for the electronic exchange between the termini via an electron hopping pathway. In order to tune the redox potential compared with those of biferrocene, one or two organoiron groups have been substituted by the Cp(PPh3)2M (M = Ru, Os) groups. In chapter IV, works are dedicated to the hybrid system Cp*(dppe)Fe-C C-TTMe3. In this molecule, electronic interactions take place between the Cp*(dppe)FeII/III center and the tetrathiafulvalene core through the ethynyl bridge. The new molecule is stable under three redox states. The mono-oxidized species behaves as a mixed valence species with an electronic coupling Hab = 320 cm-1 between the two electrophores. In the fifth and final chapter, the discovery of a CH bond activation of a methyl group located on the same cycle of the TTF core and the iron acetylide for the compound [Cp*(dppe)Fe-C C-TTMe3](PF6)3 is reported. This new reaction allows the synthesis of the multicomponent molecule [Cp*(dppe)Fe=C=C=TTFMe2=CH-CH=TTFMe2=C=C=Fe(dppe)Cp*][PF6]2 in good yield. The resulting device displays specific properties analysed with the support of the quantum chemistry.RENNES1-Bibl. électronique (352382106) / SudocSudocFranceF

Recent Developments in the Meyer-Schuster Rearrangement

International audienceA century after its discovery, the Meyer-Schuster rearrangement appears as a very useful method to prepare α,β-unsaturated carbonyl derivatives. This comprehensive review highlights the progress of this reaction during the last decade focusing on the new catalysts, the novel cascade reactions, the brilliant applications in total synthesis of natural products, and the first examples of aza-Meyer-Schuster rearrangement

Novel 2,2′-bipyridine containing two (η2-dppe)(η5-C5Me5)Fe-C[triple bond, length as m-dash]C- redox-active units with an exceptionally spatially demanding substitution pattern

International audienceSynthetic approaches to 6,6′-disubstituted-2,2′-bipyridine ligands bearing two redox active (η2-dppe)(η5-C5Me5)Fe-C[triple bond, length as m-dash]C- moieties are described. The target complex 6,6′-{(η2-dppe)(η5-C5Me5)Fe-C[triple bond, length as m-dash]C}2(2,2′-bipyridine) (6) was obtained in 79% yield as an orange powder from the reaction between the iron chloride (η2-dppe)(η5-C5Me5)Fe-Cl (9) and the 6,6′-bis(trimethylsilylethynyl)-2,2′-bipyridine (14) in the presence of KF and KPF6 in a 3 : 1 methanol/THF mixture. When reacted with 2 equiv. of [(C5H5)2Fe][PF6], 6 provided the stable bis-iron(III) complex 6[PF6]2 in 89% yield which was characterized by an X-ray crystal structure. The substitution pattern of the novel metallo-ligand 6 is so spatially demanding that it does not react with CuCl, [Cu(CH3CN)4][PF6] and PtCl2, even in drastic conditions. Nevertheless, compound 6 reacts smoothly with ZnCl2 to provide the zinc adduct ZnCl2(6), the spectroscopic properties of which evidence the Lewis acidic character of zinc dichloride

α-β Unsaturated Acylsilanes as Surrogates of Acrolein for Morita-Baylis-Hillman Reactions

International audienceα‐β‐unsaturated acylsilanes are excellent substrates for Morita–Baylis–Hillman (MBH) reactions, affording the expected adducts in good to excellent yields. In these derivatives, as well as the corresponding acetates, the acylsilanes can be smoothly transformed into aldehydes by irradiation at 365 nm in acetone or THF/water mixtures. Therefore α‐β unsaturated acylsilanes are very useful surrogates for acrolein in MBH reactions, allowing easy preparation of simple and highly functionalized new building blocks for synthetic applications

Anodic oxidation of indenofluorene. Electrodeposition of electroactive poly(indenofluorene)

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Synthesis, Spectro-Electrochemical and EPR Spectroscopical Studies of Mixed Bis(alkynyl)biferrocenes of Type (LnMCºC)(LnM'CºC)bfc

International audienceABSTRACT: The synthesis and properties of a series of complexes containing bis(ethynyl)biferrocene as a bridge between different redoxactive group 8 metal fragments is described. These metal acetylide compounds of type (LnMCC)(LnM′CC)bfc (5a, LnM = Fe(Cp*)-(η2-dppe), LnM′ = Ru(Cp)(Ph3P)2; 5b, LnM = Fe(Cp*)(η2-dppe), LnM′ = Os(Cp)(Ph3P)2; 5c, LnM = Ru(Cp)(Ph3P)2, LnM′ = Os(Cp)(Ph3P)2; bfc = biferrocene-1′,1‴-diyl, ((η5-C5H4)2Fe)2; dppe = 1,2-bis(diphenylphosphino) ethane, C2H4(PPh2)2; Cp = η5-C5H5, Cp* = η5-C5Me5) were prepared either by treatment of (HCC)(LnM′CC)bfc (LnM′ = Ru(Cp)(Ph3P)2 (4b), Os(Cp)(Ph3P)2 (4c)) with Fe(Cp*)(η2-dppe)Cl (2a) or by the reaction of 4c with Ru(Cp)(PPh3)2Cl (2b) in the presence of [H4N][PF6] and KOtBu, respectively. Compounds 5a−c show wellseparated reversible one-electron redox events in their cyclic voltammograms using [nBu4N][PF6] as supporting electrolyte in dichloromethane solutions. Absorption and vibrational spectroscopic studies were achieved for mixed-valence 5a−c[PF6] and 5a−c[PF6]2 by spectroelectrochemical methods (OTTLE), and in the case of the more robust Fe/Os system the higher oxidation states 5b[PF6]3 and 5b[PF6]4 were also characterized. Taken as a whole, our data indicate that direct electron transfer between the redox termini does not take place. Electron exchange results from dominant interactions between the redox termini and the proximal fc units (fc = Fe(η5-C5H4)2) of the bfc moiety and a weak but sizable interaction between the fc units. Furthermore, EPR spectroscopy of 5a−c[PF6] allowed the simultaneous observation of the EPR signatures of half-sandwich metal-centered radicals and biferrocenium-centered radicals. This feature strongly supports that a multistep electron exchange mechanism takes place between the MLn/M′Ln redox termini of this molecular array, with bridge-centered low-lying mediating states thermally populated even at 66 K. The g tensors of anisotropy (Δg = g∥ − g⊥) of the bis(ethynyl)biferrocenyl moiety ranging between 2.26 and 2.42 for 5a−c[PF6] are consistent with a slow electron exchange rate between the fc units and confirmed that these mixed-valence complexes belong to class II compounds as defined by Robin and Day