Trans-stereochemistry from the insertion of alkynes into a ruthenium - carbon bond of a bridging-phenyl ligand

Abstract

The reaction of Ru5(μ5-C)(CO)13(μ-η2-Ph)[μ-Au(NHC)], 1, NHC = 1,3-bis(2,6-diisopropylphenyl-imidazol-2-ylidene) with ethyne (C2H2) yielded the new compound Ru5(μ5-C)(CO)13[μ-η2-E-C(H)C(H)Ph][μ-Au(NHC)], 2 in 89 % yield. Compound 2 contains a square-pyramidal cluster of five ruthenium atoms with a carbido ligand in the base of the square pyramid and a bridging σ+π-coordinated 2-phenylvinyl ligand, μ−η2-E-CHCHPh, formed by an overall trans-insertion of the C2H2 into the Ru-C bond to the bridging η2-Ph ligand in 1. A similar reaction of 1 with phenylacetylene (PhC2H) yielded the new compound Ru5(μ5-C)(CO)13[μ-η2-Ε-C(Ph)C(H)Ph][μ-Au(NHC)], 3 in 96 % yield. Compound 3 contains a bridging σ+π-coordinated, η2-1,2-diphenylvinyl ligand, η2-E-C(Ph)C(H)Ph, formed by an overall trans-insertion of the molecule of PhC2H into the Ru-C bond of the bridging η2-phenyl ligand in 1. The phenyl ligand was shifted to the unsubstituted carbon atom of the PhC2H molecule.