Synthesis, structures and dynamic NMR spectra of eta6-hexaethylbenzene complexes of ruthenium(0) and ruthenium(II) (Articolo in rivista)

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Label
  • Synthesis, structures and dynamic NMR spectra of eta6-hexaethylbenzene complexes of ruthenium(0) and ruthenium(II) (Articolo in rivista) (literal)
Anno
  • 2002-01-01T00:00:00+01:00 (literal)
Alternative label
  • Baldwin R., Bennett M.A., Hockless D.C.R., Pertici P., Verrazzani A., F. Marchetti, G. Uccello Barretta, Salvadori P. (2002)
    Synthesis, structures and dynamic NMR spectra of eta6-hexaethylbenzene complexes of ruthenium(0) and ruthenium(II)
    (literal)
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  • Baldwin R., Bennett M.A., Hockless D.C.R., Pertici P., Verrazzani A., F. Marchetti, G. Uccello Barretta, Salvadori P. (literal)
Pagina inizio
  • 4488 (literal)
Pagina fine
  • 4496 (literal)
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  • Nuovo metodo sintetico per preparare complessi arenici di rutenio, di importanza in sintesi organometallica e catalisi omogenea, e relativo studio stereochimico. (literal)
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  • Pubblicazione su rivista internazionale (literal)
Note
  • ISI Web of Science (WOS) (literal)
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  • CNR-ICCOM, Sezione di Pisa; Dipartimento di Chimica e Chimica Industriale Università di Pisa; Research School of Chemistry, Australian National University, Camberra, Australia (literal)
Titolo
  • Synthesis, structures and dynamic NMR spectra of eta6-hexaethylbenzene complexes of ruthenium(0) and ruthenium(II) (literal)
Abstract
  • On reaction with the labile naphthalene complex [Ru(eta6-C10H8)(eta4-1,5-COD)], hex-3-yne undergoes stoichiometric cyclotrimerisation to form the hexaethylbenzene–ruthenium(0) complex [Ru(eta6-C6Et6)(eta4-1,5-COD)]1. In the solid state and in solution the ethyl groups adopt a 1,4-proximal-2,3,5,6-distal arrangement, as shown by X-ray crystallography and NMR (1H, 13C-{1H}) spectroscopy. Treatment of 1 with HCl gives the binuclear ruthenium(II) complex [{RuCl(eta6-C6Et6)}2(µ-Cl)2]2, whose arene ligands adopt a transoid arrangement about the Ru2Cl2 moiety; in turn 2 reacts with methanolic NH4PF6 to give the salt [Ru2(µ-Cl)3(eta6-C6Et6)2]PF6, [3]PF6. The ethyl group conformations in crystalline 2 and [3]PF6 are all-distal and 1,3,5-proximal-2,4,6-distal, respectively, whereas only the latter conformation is present in both compounds in dichloromethane or methanol solutions at low temperature according to 13C-{1H} NMR spectroscopy. The (Ru–Cl) band patterns in the IR spectra of 2 in the solid state and dichloromethane solution are almost identical, indicating that the neutral di-µ-chloro species predominates in solution at room temperature. However, the appearance at –50 °C of a resonance due to free chloride ion in the 35Cl NMR spectrum of complex 2 suggests that reversible formation of [3]Cl may be favoured at low temperature. Dilute (ca. 10–3 M) solutions of 2 in dichloromethane and methanol behave as 1 1 electrolytes consistent with the presence of [3]Cl under these conditions. At room temperature the ethyl groups of eta6-C6Et6 in 1, 2 and [3]PF6 are equivalent on the NMR time-scale as a consequence of rotation about the arene–methylene bond and, possibly, rotation of the arene about the arene–metal bond. In the crystalline adducts [RuCl2(eta6-C6Et6)(L)](L = PMe34, PPh35) the ethyl groups are all distal and remain equivalent on the NMR time-scale in solution from room temperature to –97 °C. The results confirm conclusions, based primarily on studies of Group 6 carbonyl complexes, that the different conformations of eta6-C6Et6 have very similar energies. (literal)
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