The oxidation reactions of the unsaturated anion [Re3(μ-H)4(CO)10]- with C7H7+ are described. They imply, as the first step, abstraction of a H- ligand, and when performed in the presence of donor species L, such as CO or RCN, they lead to the neutral derivatives Re3(μ-H)3(CO)10L2. In the absence of donor molecules, in inert solvents, the new species Re3H2(CO)10(η-C7H9) is readily obtained in high yields. It has been investigated by single-crystal X-ray analysis. The crystals are monoclinic, space group C2/c, with cell constants a = 31.507 (7) Å, b = 8.561 (3) Å, c = 16.503 (4) Å, β = 106.60 (2)°, and Z = 8. The structure was solved by Patterson and Fourier methods and refined by least-squares techniques, on the basis of 2677 significant independent counter data, up to a final R value of 0.027. The molecule contains a triangular arrangement of rhenium atoms. Two metals, Re2 and Re3, each bear four terminal CO groups, while Re1 is linked to two such ligands and to the η5-cycloheptadienyl ligand. The two hydrides have been indirectly located, one double-bridging the Re2-Re3 edge and the second one in a triple-bridging location. Rhenium-rhenium bond lengths are Re1-Re2 = 3.160 (1) Å, Re1-Re3 = 3.193 (1) Å, and Re2-Re3 = 3.076 (1) Å. 1H and 13C NMR analyses at different temperatures indicate a fluxional behavior in solution of the C7H9 group, involving also the scrambling of the two CO groups bound to Re1. The apparent C2v. symmetry for the whole compound at room temperature has been interpreted as deriving from a complete interchange of the coordination sites of the ligands bound to Re1, accompanied by a concerted up and down movement of the μ3-H ligand through the Re3 plane. At-100°C the 10 CO groups and all the hydrogen atoms of the C7H9 ligand display different resonances, in accordance with the lack of symmetry of the solid-state structure. © 1984 American Chemical Society.

Synthesis, crystal structure, and fluxional behavior of Re3H2(CO)10(η5-C 7H9) / T. Beringhelli, G. Ciani, G. D'Alfonso, P. Romiti, A. Sironi, M. Freni. - In: INORGANIC CHEMISTRY. - ISSN 0020-1669. - 23:18(1984), pp. 2849-2852.

Synthesis, crystal structure, and fluxional behavior of Re3H2(CO)10(η5-C 7H9)

T. Beringhelli
Primo
;
G. Ciani
Secondo
;
G. D'Alfonso;A. Sironi
Penultimo
;
1984

Abstract

The oxidation reactions of the unsaturated anion [Re3(μ-H)4(CO)10]- with C7H7+ are described. They imply, as the first step, abstraction of a H- ligand, and when performed in the presence of donor species L, such as CO or RCN, they lead to the neutral derivatives Re3(μ-H)3(CO)10L2. In the absence of donor molecules, in inert solvents, the new species Re3H2(CO)10(η-C7H9) is readily obtained in high yields. It has been investigated by single-crystal X-ray analysis. The crystals are monoclinic, space group C2/c, with cell constants a = 31.507 (7) Å, b = 8.561 (3) Å, c = 16.503 (4) Å, β = 106.60 (2)°, and Z = 8. The structure was solved by Patterson and Fourier methods and refined by least-squares techniques, on the basis of 2677 significant independent counter data, up to a final R value of 0.027. The molecule contains a triangular arrangement of rhenium atoms. Two metals, Re2 and Re3, each bear four terminal CO groups, while Re1 is linked to two such ligands and to the η5-cycloheptadienyl ligand. The two hydrides have been indirectly located, one double-bridging the Re2-Re3 edge and the second one in a triple-bridging location. Rhenium-rhenium bond lengths are Re1-Re2 = 3.160 (1) Å, Re1-Re3 = 3.193 (1) Å, and Re2-Re3 = 3.076 (1) Å. 1H and 13C NMR analyses at different temperatures indicate a fluxional behavior in solution of the C7H9 group, involving also the scrambling of the two CO groups bound to Re1. The apparent C2v. symmetry for the whole compound at room temperature has been interpreted as deriving from a complete interchange of the coordination sites of the ligands bound to Re1, accompanied by a concerted up and down movement of the μ3-H ligand through the Re3 plane. At-100°C the 10 CO groups and all the hydrogen atoms of the C7H9 ligand display different resonances, in accordance with the lack of symmetry of the solid-state structure. © 1984 American Chemical Society.
Settore CHIM/03 - Chimica Generale e Inorganica
1984
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/184000
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