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111.
Jean-Yves Saillard Samia Kahlal Vincent Ferrand Helen Stoeckli-Evans Georg Süss-Fink 《Journal of organometallic chemistry》2001,620(1-2):119-126
Triruthenium clusters containing a methylphenylsulfoximido cap or bridge, Ru3(CO)9(μ2-H)[μ3-NS(O)MePh] (1), Ru3(CO)10(μ2-H)[μ3-NS(O)MePh] (2), Ru3(CO)8(μ3-η2-CPhCHBu)[μ3-NS(O)MePh] (3), Ru3(CO)9(μ3-η2-PhCCCCHPh)[μ2-NS(O)MePh] (4), and Ru3(CO)7(μ2-CO)(μ3-η2-PhCCCCHPh)[μ3-NS(O)MePh] (5) have been examined by EHT and DFT calculations in order to analyze the bonding present in the clusters and to establish the electron counting. They clearly show that a μ3-sulfoximido group is not a 3e− ligand as one may be led to think at first sight, but rather acts as a three-orbital/5e− system, i.e. should be considered as isolobal to an N---R− ligand. Because of some delocalization of its π-type orbitals on the sulfur and oxygen atoms, it is expected to bind slightly less strongly to metal atoms than classical imido ligands. Once in a μ2 coordination mode, the sulfoximido ligand retains a lone pair on its pyramidalized N atom and becomes a two-orbital/3e− ligand. It follows that clusters 1, 2, 4 and 5 are electron-precise, whereas cluster 3 is electron deficient with respect to the 18e− rule but obeys the polyhedral skeletal electron pair electron-counting rules. Consistently, all the calculated clusters exhibit large HOMO–LUMO gaps and no trace of electron deficiency can be found in their electronic structures. 相似文献
112.
We report a new method for preparation of hydroxyacids as precursors of benzolactones using a simple and an efficient electrochemical step. This gives in only four steps six- to eleven-membered lactones with high isolated yields from conveniently substituted aryl bromides. The lactonisation was performed according to the Yamamoto's process. 相似文献
113.
Jean-Franois Devaux Pierre Fraisse Issam Hanna Jean-Yves Lallemand 《Tetrahedron letters》1995,36(52):9471-9474
An unprecedented remote effect of the hydroxyl group on π-facial selectivity was observed in the addition of Grignard reagents to bicyclo[2.2.2]octan-2-ones, where nucleophilic attack occured from the slerically more hindered face. 相似文献
114.
Bachir Zouchoune Jean-Yves Saillard Jean-François Halet 《Journal of Cluster Science》2007,18(3):720-728
DFT calculations show that the optimal metal valence electron (MVE) count of omnicapped cubic rhodium clusters containing
more than eight terminal ligands, is 114. For such a count, a closed-shell configuration is computed with a substantial HOMO-LUMO
gap. The presence of more than eight terminal ligands in the clusters favors highly distorted cubic architectures with capping
ligands asymmetrically bound to the distorted metallic square faces. Removal of terminal ligands leads to the replacement
of bonding M–L electron pairs by nonbonding electron pairs localized on the metal atoms, giving rise to unchanged MVE count. 相似文献
115.
Sans résumé
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116.
117.
We first build the moduli spaces of real rational pseudo-holomorphic curves in a given real symplectic 4-manifold. Then, following the approach of Gromov and Witten [3, 19, 11], we define invariants under deformation of real symplectic 4-manifolds. These invariants provide lower bounds for the number of real rational J-holomorphic curves which realize a given homology class and pass through a given real configuration of points. Mathematics Subject Classification (2000) 14N10, 14P25, 53D05, 53D45 相似文献
118.
Jean-Yves Charbonnel 《Mathematische Annalen》1980,250(1):1-34
Sans résumé 相似文献
119.
Jean-Yves Godet Michel Pereyre Jean-Claude Pommier Daniel Chevolleau 《Journal of organometallic chemistry》1973,55(1):C15-C18
The ability of tris[(S)-2-methylbutoxyl] aluminum to bring about asymmetric reduction of methyl ethyl ketone has been reinvestigated: only a low stereoselectivity has been observed. 相似文献
120.
Previous low resolution studies indicated that, in the absorption spectrum, transitions to Rydberg states are far more sensitive to pressure than transitions to valence states in accordance with the complete vanishing of Rydberg bands and the deperturbation of the valence bands in the spectrum of NO trapped in a solid rare gas matrix. The present study of NO is the first extensive investigation of medium and high resolution molecular electronic spectra subjected to pressure of foreign gases. It is observed that, at the highest pressure attained (~1000 bar), almost all of the Rydberg bands have vanished whereas the remaining valence bands stay relatively sharp. While high pressure medium resolution spectra give information about the deperturbation of intensities and of vibrational spacings of the valence bands, inspection of low pressure high resolution spectra reveals that the rotational lines react to pressure in a way reflecting closely the degree of configuration mixing between Rydberg and valence states. 相似文献