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- PublicationMétadonnées seulement[(eta(6)-p-Pr(i)C6H4Me)(2)Ru2Mo2O6(OMe)(4)]: a new tetranuclear mixed-metal oxo cluster presenting a cube-based chair structureThe title complex was obtained by reaction of [(eta(6)-p-Pr'C6H4Me)(4)Ru4Mo4O16] with methanol in the presence of p-hydroquinone. It contains an Mo2Ru2O2(OMe)(4) core consisting of two Mo2RuO(OMe)(3) half-cubes fused together to form a choir-like structure. (C) 1999 Elsevier Science S.A. All rights reserved.
- PublicationMétadonnées seulementDi-mu-bromo-bis[bromo(eta(6)-para-cymene)-ruthenium(II)] benzene solvate and di-mu-iodo-bis[(eta(6)-para-cymene)iodoruthenium(II)] toluene solvateThe homologous title molecules, [Ru2Br4(C10H14)(2)]. C6H6, (1), and [Ru2I4(C10H14)(2)]. C7H8, (2), consist of arene-ruthenium moieties [Ru-to-ring distances of 1.655 (2) Angstrom in (1) and 1.673(3) Angstrom in (2)] with a terminal halogen ligand and [Ru-Br 2.548 (1) Angstrom in (1) and Ru-I 2.726(1) Angstrom in (2)], held together by two symmetrical halogen bridges [Ru-Br 2.575(1) Angstrom in (1) and Ru-I 2.736(1) Angstrom in (2)]. The arene rings are planar and parallel to each other, and the terminal halogen ligands are coordinated to rurthenium trans with respect to each other. Both molecules possess C-i symmetry.
- PublicationMétadonnées seulementThe cluster dication [H6Ru4(C6H6)(4)](2+) revisited: the first cluster complex containing an intact dihydrogen ligand?A low-temperature H-1-NMR study suggests the tetranuclear cluster dication [H6Ru4(C6H6)(4)](2+) (1) to contain an H-2 ligand that undergoes, upon warming of the solution, an intramolecular exchange with the four hydride ligands at the Ru-4 framework. Whereas two of the three NMR signals at - 120 degrees C in the hydride region show T-1 values in the range 200-300 ms, the least deshielded resonance at delta = - 17.33 ppm exhibits a T-1 value of only 34 ms, characteristic of an H-2 ligand. a re-examination of the single-crystal X-ray structure analysis of the chloride salt of 1 supports this interpretation by a short distance of 1.14(0.15) Angstrom between two hydrogen atoms coordinated as a PI-PI ligand in a side-on fashion to one of the triangular faces of the Ru-4 tetrahedron. The distance between one of the two hydrogen atoms of the H-2 ligand and one of the four hydride ligands is also very short [1.33(0.15) Angstrom], suggesting an additional H-2... H interaction. The presence of this H-3, unit over one of the three Ru-3 faces in 1 may explain the deformation of the Ru-4 skeleton from the expected tetrahedral symmetry. Density functional theory (DFT) calculations on 1 indicate a very soft potential energy surface associated with the respective displacement of the three interacting cofacial hydrogen atoms. In accordance with these results, the cluster dication 1 tends to loose molecular hydrogen to form the cluster dication [H4Ru4(C6H6)(4)](2+) (2). The equilibrium between 1 and 2 can be used for catalytic hydrogenation reactions. (C) 2000 Elsevier Science S.A. All rights reserved.