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Jacques E. Guerchais

Bio: Jacques E. Guerchais is an academic researcher from University of Western Brittany. The author has contributed to research in topics: Crystal structure & Cyclopentadienyl complex. The author has an hindex of 15, co-authored 83 publications receiving 799 citations.


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TL;DR: In this paper, the structure of the trans isomer has been established by X-ray diffraction, and the structure was solved by heavy-atom methods and refined to R 0.026 (R′ 0.031) for 4 092 independent intensities.
Abstract: Upon treatment with methyl-lithium followed by HBF4·OEt2 a carbon monoxide ligand of the µ-alkylidene complex [Ru2(CO)2(µ-CO)(µ-CMe2)(η-C5H5)2](1) is converted into µ-ethylidyne, giving [Ru2(CO)2(µ-CMe)(µ-CMe2)(η-C5H5)2]+(2). This is deprotonated readily by water to form the µ-vinylidene complex [Ru2(CO)2(µ-CCH2)(µ-CMe2)(η-C5H5)2](3), which quantitatively regenerates (2) with HBF4·OEt2. Addition of NaBH4 to (2) results in hydride attack on µ-CMe to yield the di-µ-alkylidene complex [Ru2(CO)2(µ-CHMe)(µ-CMe2)(η-C5H5)2](4) as cis and trans isomers. The structure of the trans isomer has been established by X-ray diffraction. Crystals are triclinic, space group P, with Z= 2 in a unit cell for which a= 8.474(2), b= 7.802(3), c= 12.989(5)A, α= 99.42(3), β= 96.96(3), and γ= 107.73(3)°. The structure was solved by heavy-atom methods and refined to R 0.026 (R′ 0.031) for 4 092 independent intensities. A ruthenium–ruthenium single bond of 2.701(1)A is symmetrically bridged by ethylidene [mean Ru–C 2.079(3)] and isopropylidene [mean Ru–C 2.107(3)A] ligands to form an approximately planar Ru2C2 ring with a non-bonding Me2C··CHMe distance of 3.20 A. Upon thermolysis the alkylidenes link to evolve Me2CCHMe, Me2CHCHCH2, and Et(Me)CCH2. The absence of C4 and C6 hydrocarbons indicates that the alkylidene coupling occurs intramolecularly, and the electronic and stereochemical requirements of this process are discussed. Unlike mono-µ-alkylidene complexes, [Ru2(CO)2(µ-CO)(µ-CR2)(η-C5H5)2], the cis and trans forms. of (4) do not interconvert thermally below 145 °C, but u.v. irradiation effects a slow trans to cis isomerisation. U.v. irradiation of (4) in the presence of dimethyl acetylenedicarboxylate promotes ethylidene–alkyne linking to form [Ru2(CO)(µ-CMe2){µ-C(CO2Me)C(CO2Me)CHMe}(η-C5H5)2], but with ethyne both of the alkylidenes are lost and the ruthenium–ruthenium double-bonded complex [Ru2(µ-CO)(µ-C2H2)(η-C5H5)2] is produced.

37 citations

Journal ArticleDOI
TL;DR: In this article, the C 10 N 7 unit was shown to have a planar geometry with central CN bond lengths of 1.317(4) and 1.334(4), 1.33(1) A in 1, 1.34(1), 1, 1.3(3), and 128.2(9)° in 2.

33 citations

Journal ArticleDOI
TL;DR: In this article, a systeme monoclinique avec le groupe d'espace C2/c is described, a system that is based on the system of C 2/c.
Abstract: [Mo(C 22 H 22 N 4 )] 2 PF 6 •CH 2 Cl 2 cristallise dans le systeme monoclinique avec le groupe d'espace C2/c. Affinement de la structure jusqu'a 0,054

31 citations

Journal ArticleDOI
TL;DR: In this paper, the first geometrical isomerization of thiolato-bridged dimolybdenum complexes induced by the transfer of two electrons at the same potential is reported.

31 citations


Cited by
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TL;DR: The factor that controls the activity of these chelates is not fully understood but parameters such as redox potentials of the metal and electronic structure appear to be crucial as discussed by the authors.

499 citations

Journal ArticleDOI
TL;DR: The reaction chemistry of nitriles with transition metal complexes is reviewed in this paper, where the authors survey data published during the period 1977-early 1994 on new reaction processes such as insertion into metal-hydrogen and carbon bonds, coupling between one nitrile and an unsaturated metal fragment, reduction to amines, attack by protic and aprotic nucleophiles and electrophilic attack as well as some catalytic transformations.

427 citations

Journal ArticleDOI
TL;DR: In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website as discussed by the authors, in case of legitimate complaints the material will be removed.
Abstract: Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible.

425 citations

Journal ArticleDOI
TL;DR: In this article, a spectroscopic and structural investigation of binuclear silver(I) complexes supported by aliphatic phosphine ligands, namely [Ag(PCy3)(O2CCF3)]2 (1), [Ag2(μ-dcpm)2]X2 (X = CF3SO3, 2; PF6, 3; dcpm = bis(dicyclohexylphosphino)methane), and [Ag 2(mdcpm)(μ-O2ccF3] (4), is described.
Abstract: A spectroscopic and structural investigation of binuclear silver(I) complexes supported by aliphatic phosphine ligands, namely [Ag(PCy3)(O2CCF3)]2 (1), [Ag2(μ-dcpm)2]X2 (X = CF3SO3, 2; PF6, 3; dcpm = bis(dicyclohexylphosphino)methane), and [Ag2(μ-dcpm)(μ-O2CCF3)2] (4), is described. X-ray structural analyses of 1−4 reveal Ag−Ag separations of 3.095(1), 2.948 (av), 2.923 (av), and 2.8892(9) A, respectively. Due to the optical transparency of the phosphine ligands, the UV−vis absorption band at 261 nm in CH3CN for 2 and 3 is assigned to a 4dσ* → 5pσ transition originating from Ag(I)−Ag(I) interactions. The argentophilic nature of this band is verified by the resonance Raman spectrum of 2 with 273.9 nm excitation, where virtually all of the Raman intensity appears in the Ag−Ag stretch fundamental (80 cm-1) and overtone bands. Complexes 2 and 3 exhibit photoluminescence in the solid state at room temperature.

315 citations