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Updated: Apr 4, 2026
The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
Formation of ruthenium carbenes by gem-hydrogen transfer to internal alkynes: implications for alkyne
Markus Leutzsch1, Larry M Wolf1, Puneet Gupta1
1Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr (Germany).
Abstract:
Insights into the mechanism of the unusual trans-hydrogenation of internal alkynes catalyzed by {Cp*Ru} complexes were gained by para-hydrogen (p-H2 ) induced polarization (PHIP) transfer NMR spectroscopy. It was found that the productive trans-reduction competes with a pathway in which both H atoms of H2 are delivered to a single alkyne C atom of the substrate while the second alkyne C atom is converted into a metal carbene. This "geminal hydrogenation" mode seems unprecedented; it was independently confirmed by the isolation and structural characterization of a ruthenium carbene complex stabilized by secondary inter-ligand interactions. A detailed DFT study shows that the trans alkene and the carbene complex originate from a common metallacyclopropene intermediate. Furthermore, the computational analysis and the PHIP NMR data concur in that the metal carbene is the major gateway to olefin isomerization and over-reduction, which frequently interfere with regular alkyne trans-hydrogenation.
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