Reaction between ferrocene-carboxaldehyde and dioxaphospholene: Characterization and crystal structures of an unexpected bisferrocenyldioxolane

CCDC 925532 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via http://www.ccdc.cam.as.uk/data_request/cifInternational audienceReacting an 1:1 stoichiometric molar ratio of ferrocenecarboxaldehyde and 2,2,2-trimethoxy-4,5-dimethyl-1,3,2-dioxaphospholene, neat, at room temperature for one week, leads to the diastereoselective formation of a bis-ferrocenyl 1,3-dioxolane complex 1-(4-methyl-2,5-diferrocenyl-1,3-dioxolan-4-yl)ethanone (1), in 30% isolated yield. The compound has been fully characterized by FT-IR, mono- and two-dimensional 1H and 13C NMR spectroscopy, elemental analysis, and cyclic voltammetry. Complex 1 has also been characterized by single crystal X-ray analysis

Two substrates, three products: Reactions between ferrocene-carboxaldehyde and dioxaphospholene, characterization and crystal structures of oxygenated C3- and C4-chain-containing ferrocenes

CCDC 893249, 893248, and 893250 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via http://www.ccdc.cam.as.uk/data_request/cif.International audienceReactions of aldehydes RCHO with 2,2,2-trimethoxy-4,5-dimethyl-1,3,2-dioxaphospholene are known to form trimethylbiacetyl-aldehyde-phosphite adducts which upon methanolysis gave rise to the corresponding symmetrical 3-R-2,4-pentanediones (R = aryl, alkyl). Reactions between ferrocenecarboxaldehyde and the biacetyl-trimethylphosphite adduct, whatever the experimental conditions used, afforded three new oxygenated C3 and C4 side-chain containing ferrocenyl complexes, namely, 1-ferrocenyl-1,2-propanedione (1, Fc-C(O)C(O)CH3; Fc = (η5-C5H5)Fe(η5-C5H4)), 4-methoxy-4-ferrocenyl-3-hydroxy-3-methyl-2-butanone (2, Fc-CH(OCH3)C(CH3)(OH)C(O)CH3) as a single diastereoisomer, and the ferrocenyl enone 4-ferrocenyl-3-methyl-3-buten-2-one (3, Fc-CHdouble bond; length as m-dashC(CH3)C(O)CH3) with the enone portion adopting the s-trans conformation in the solid state. The compounds readily purified by silica gel packed column chromatography were isolated in 31-44% yields, and their constitution is in agreement with elemental analyses, IR and multinuclear NMR spectroscopy, and electrospray mass spectrometry. Their molecular identity and geometry have been confirmed by single-crystal X-ray diffraction

Theoretical and electrochemical studies on organometallic symmetrical schiff base complexes of Zn(II), Cu(II), Ni(II) and Co(II).

International audienceThe electronic communication between two redox centres through a Schiff base complex has been investigated in a series of ethylenediimine-bis(1-ferrocenyl-1,3-butanedionate) complexes of Zn(II) 1, Cu(II) 2, Ni(II) 3 and Co(II) 4. Cyclic voltammetry experiments of 1 and 2 exhibit a unique two-electron reversible oxidation wave, whereas in the case of 3 and 4 two and three one-electron oxidation processes are, respectively, observed. These results suggest some electronic interaction between the iron atoms of the ferrocenyl groups. DFT calculations carried out on model complexes show that for all the studied compounds the removal of the first two electrons corresponds to the oxidation processes of the iron centres in the weakly coupled ferrocenyl termini. The electronic communication between the two iron centres increases on going from 1 to 4. Finally, a re-indexation of the bands observed in the UV-Visible spectra has been carried out using TDDFT calculations

Synthesis, characterization and X-ray crystal structures of chiral ferrocene-containing β-diketones

CCDC 922490, 922491, and 922492 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.International audienceThree new chiral ferrocene-containing β-diketones have been synthesized by reacting 1-ferrocenyl ethanol with the corresponding 1,3-diketone reagent MeCOCH2COR (R = Me, 4-C6H4OMe, Fc; Fc = (η5-C5H5)Fe(η5-C5H4)), using cerium(IV) ammonium nitrate (CAN) mediated C-C bond formation. These compounds identified as 3-(1-ferrocenylethyl)-pentane-2,4-dione (1), 1-(4-methoxyphenyl)-2-(1-ferrocenylethyl)-butane-1,3-dione (2), and 1-ferrocenyl-2-(1-ferrocenylethyl)-butane-1,3-dione (3), have been isolated as air and thermally stable microcrystalline solids in 79, 63 and 44% yields, respectively. Compounds 2 and 3 were formed in 63:37 and 88:12 diastereomeric ratios, respectively. They have been fully characterized by elemental analyses, FT-IR spectra, mass spectrometry, and their complete assignments have been conducted using 2D NMR experiments. In addition, their molecular identity and geometry have been confirmed by single-crystal X-ray diffraction, and both solution and solid state measurements have shown that the three complexes exist solely as their diketo tautomers

A Facile Access to New Polymethylmethacrylate-Anchored Ferrocene Substituted Nickel(II) Unsymmetrical Schiff Base Complexes: Synthesis and Characterization.

International audienceThis paper discloses two new side-chain metallopolymers containing an unsymmetrical organometallic Schiff base complex of Ni(II) linked to a polymethylmethacrylate (PMMA) matrix. The neutral ferrocene substituted Schiff base complex 1, Ni{CpFe(η5-C5H4)-C(O)CH=C(CH3)N-o-C6H4N=CH-(2-O,5-OH-C6H3)} where (Cp = η5-C5H5), was synthesized via template reaction by condensation of the tridentate half-unit metalloligand Fc-C(O)CH=C(CH3)-N(H)-o-C6H4NH2 (Fc = ferrocenyl = CpFe(η5-C5H4)) with 2,5-dihydroxybenzaldehyde in the presence of nickel(II) acetate tetrahydrate. The binuclear Schiff base complex of Ni(II) containing an aromatic free hydroxyl group was reacted under basic conditions with PMMA to afford, upon trans-esterification reaction, metallopolymers 2 (complex 1 monomeric unit/PMMA = 1/5) and 3 (complex 1 monomeric unit/PMMA = 1/3). Elemental analysis, FT-IR, 1H and 13C NMR spectroscopies, and cyclic voltammetry were utilized to characterize the newly synthetized compounds. Surface morphology of the metallopolymer film of 2 was studied using atomic force microscopy

Deacetylation of chiral ferrocenyl-containing β-diketones promoted by ethylene diamine: Spectroscopic and structural characterization of the fragmentation products

International audienceIt is well known that β-diketones react with primary amines, readily forming thecorresponding Schiff base derivatives. However, in the present case, the chiralferrocenyl-containing β-diketones, 3-(1-ferrocenylethyl)-pentane-2,4-dione (1a), 1-(4-methoxyphenyl)-2-(1-ferrocenylethyl)-butane-1,3-dione (1b), and 1-ferrocenyl-2-(1-ferrocenylethyl)-butane-1,3-dione (1c) react with ethylene diamine under acidicconditions in refluxing toluene to yield, unexpectedly, their deacetylated counterparts,3-ferrocenyl-butane-2-one (2a), 1-(4-methoxyphenyl)-3-ferrocenyl-butane-1-one (2b),and 1,3-bisferrocenyl-butane-2-one (2c), respectively. Such deacetylation reactions areaccompagned by the formation of 2-methyl-2-imidazoline. A reaction mechanisminvolving an intramolecular Michael addition followed by a retro-Mannichrearrangement is suggested. The ketones 2a-c are fully characterized by analytical andspectroscopic methods. Additionally, compounds 2a and 2c are authenticated by singlecrystal X-ray diffraction analysis. The electrochemical behaviour of the bimetalliccomplex 2c is also investigated

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

Anisyl and ferrocenyl adducts of methylenepyran-containing β-diketone: Synthesis, spectral, structural, and redox properties

International audienceWittig reaction between the in situ generated [2,6-diphenyl-4H-pyran-4-yl phosphorane and methyl 4-formylbenzoate afforded the methyl 4-[(2,6-diphenyl-4H-pyran-4-ylidene)methyl]benzoate precursor 2 in 75% yield. The anisyl and ferrocenyl adducts of methylenepyran-containing β-diketones 3 and 4, respectively, were prepared from the base-catalyzed Claisen condensation reaction between precursor 2 and 4-methoxyacetophenone or acetylferrocene, using t-BuO−K+ as basic initiator. Both β-diketones 3 and 4 were isolated as an orange and dark-red crystalline solids in 50% yield, respectively. The acetyl derivative 6, 1-acetyl-1′-methylenepyranyl-ferrocene, was synthesized following a classical Friedel-Crafts acylation reaction of the parent ferrocenylmethylenepyran 5, and isolated in 61% yield as a red microcrystalline powder. The condensation reaction between the electron-rich acetyl complex 6 and acetyl acetate, using lithium diisopropylamide as the active base initiator, provided the ferrocenylmethylenepyran-containing β-diketone, 1-(1,3-dioxobutyl)-1′-[(2,6-diphenyl-4H-pyran-4-ylidene)methyl] ferrocene 7, isolated in 20% yield as an orange powder. The composition and identity of the new compounds 2-4, 6 and 7 are supported by elemental analysis, FT-IR, one- and two-dimensional 1H and 13C NMR spectral data and mass spectrometry. Additionally, the molecular structures of compounds 2, 4 and 6 were ascertained by single-crystal X-ray diffraction study. FT-IR and NMR spectral data indicate that both β-diketones 3 and 4 do solely exist as their keto-enol tautomeric form in solution and in the solid state, whereas a mixture of keto-enol and β-diketone tautomers in a 73:27 spectroscopic ratio was observed for 7. In the three cases, enolization takes place exclusively away from the anisyl or ferrocenyl group with formation of a six-membered pseudo-aromatic keto-enol ring, confirmed by the crystal structure of 4. Cyclic voltammetric measurements revealed that all the compounds undergo a single one-electron oxidation, localized presumably at the methylenepyran unit. This first oxidation generates a radical cation that undergoes an intermolecular C-C bond coupling to form the corresponding dimer. Anodically shifted to the first oxidation, cyclovoltammogram of 4 exhibits one reversible two-electron oxidation while that of 6 and 7 present two successive reversible one-electron oxidations, attributed in the three cases to the ferrocenyl fragment of the dimer

Parkin Deficiency Delays Motor Decline and Disease Manifestation in a Mouse Model of Synucleinopathy

In synucleinopathies, including Parkinson's disease, partially ubiquitylated α-synuclein species phosphorylated on serine 129 (PS129-α-synuclein) accumulate abnormally. Parkin, an ubiquitin-protein ligase that is dysfunctional in autosomal recessive parkinsonism, protects against α-synuclein-mediated toxicity in various models

Foreword to the special issue of Polyhedron dedicated to Professor Claude Lapinte.

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