Facile Insertion of Terminal Acetylenes into the Ru^II−NR₂ Bond of a 14-Valence-Electron Complex

The reaction of alkynes RC⋮CH (R = H, Ph) with (PNP)RuCl, where PNP is (tBu2PCH2SiMe2)2N, occurs rapidly below 23 °C to give first an η2-alkyne adduct and then a final product with a vinylidene group, CCHR, inserted into the N−Ru bond. Characterization included X-ray diffraction (R = Ph) and DFT calculations to probe mechanistic aspects of the reaction.