Hydride Is Not a Spectator Ligand in the Formation of Hydrido Vinylidene from Terminal Alkyne and Ruthenium and Osmium Hydrides: Mechanistic Differences
Citations Over TimeTop 10% of 1998 papers
Abstract
RuHX(H2)L2 (L = PtBu2Me; X = Cl, I) and OsH3ClL2 (L = PiPr3) react (time of mixing) with terminal alkynes in a 1:2 stoichiometry to give MHX(CCHR)L2 and RCHCH2. The reactions of RuHX(H2)L2 with PhC⋮CD lead to RuDX(CCHPh)L2 as the only isotopomers. This result is understood in terms of an insertion of the alkyne in the Ru−H bond to make a vinyl, followed by an α-hydrogen migration, giving the hydrido/vinylidene. This reaction path has been studied by ab initio (B3LYP) calculations with location of the minima and transition states. In agreement with isotopic labeling experiments, it is shown that the path starting with insertion into the Ru−H bond is more favorable than a 1,2-migration within the coordinated alkyne ligand. The favored reaction is calculated to be exothermic from the starting compounds to intermediates and to products with the energies of all transition states well below that of the separated reactants. The mechanism involves the formation of a 14-electron η1-vinyl intermediate which, after structural changes, gives the 16-electron hydrido/vinylidene product. The same general reaction path is calculated to be preferred for Os, but differences occur between the geometries of the vinyl intermediate (it is η2-vinyl for Os) and in the total number of intermediates involved.
Related Papers
- → A Stable Four-Membered N-Heterocyclic Carbene(2004)139 cited
- → Structural aspects of the osmium and ruthenium clusters [M3(CO)10(alkyne)] and related substituted compounds(1992)24 cited
- → tBu2PF as a ligand in tri-osmium clusters(1995)12 cited
- → Unusual regioselectivity in iodoplatination of the C—C triple bond of methyl propiolate in the MeI–PtII–NaI–acetone system(2012)1 cited
- → The Surface of Inorganic Oxides: An Unusual Reaction Medium for the High‐Yield and Selective Synthesis of Various Osmium Carbonyl Clusters(1999)5 cited