Jump to main content
Jump to site search

Issue 20, 2004
Previous Article Next Article

Acetylene to vinylidene rearrangements on electron rich d6 metal centers: a density functional study

Author affiliations

Abstract

The acetylene to vinylidene isomerization on several Ru(II) d6 metal fragments with different electron richness of the metal center has been investigated by means of density functional theory calculations. We considered the [(η5-C5Me5)Ru(dippe)]+, [(η5-C5Me5)Ru(dmpe)]+, [(η5-C5H5)Ru(PMe3)2]+, [(η6-C6Me6)(PMe3)ClRu]+, [(η5-C5H5)Ru(CO)(PPh3)]+ and [(η6-C6H6)(PMe3)ClRu]+, species which are quite common in the chemistry of cationic Ru(II) complexes and span a wide range of electron-richness. For each of the considered fragments, the minima on the potential energy surfaces for the two possible isomerization mechanisms, i.e. through a direct 1,2-hydrogen shift or through a hydrido–alkynyl intermediate, have been localized. A linear correlation has been found between the C[double bond, length as m-dash]C stretching frequencies of the vinylidene complexes, as an estimate of the electron richness, and the stability of the corresponding hydrido–alkynyl intermediates. For the most electron-rich among the considered fragments, [(Cp*)(dippe)Ru(HCCH)]+, the hydrido–alkynyl species has been found essentially isoenergetic with the alkyne complex (only 1.9 kcal mol−1 higher), in agreement with the experimental evidence showing for this system an equilibrium between these two species. For the same [(Cp*)(dippe)Ru]+ fragment, a detailed analysis of the reaction profiles for the two possible acetylene rearrangement pathways has been performed. Our results show that once the η2-C–H coordinated acetylene intermediate is accessed, the system can easily evolve towards a hydrido–alkynyl intermediate, this process being kinetically favored with respect to the direct 1,2-shift leading to the vinylidene product.

Graphical abstract: Acetylene to vinylidene rearrangements on electron rich d6 metal centers: a density functional study

Back to tab navigation

Publication details

The article was received on 03 Jun 2004, accepted on 21 Jul 2004 and first published on 27 Aug 2004


Article type: Paper
DOI: 10.1039/B408452G
Citation: Dalton Trans., 2004,0, 3225-3230
  •   Request permissions

    Acetylene to vinylidene rearrangements on electron rich d6 metal centers: a density functional study

    F. De Angelis, A. Sgamellotti and N. Re, Dalton Trans., 2004, 0, 3225
    DOI: 10.1039/B408452G

Search articles by author

Spotlight

Advertisements