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Terminal‐Alkyne‐Induced Decomposition of a Phosphine‐Free Ruthenium Alkylidene Catalyst
Author(s) -
Gierada Maciej,
Czeluśniak Izabela,
Handzlik Jarosław
Publication year - 2017
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201601647
Subject(s) - ruthenium , phenylacetylene , imes , alkyne , chemistry , catalysis , phosphine , medicinal chemistry , photochemistry , stereochemistry , carbene , organic chemistry
The transformations of the third‐generation Grubbs catalyst [RuCl 2 (=CHPh)(3‐Br‐py) 2 (H 2 IMes)] (py=pyridine, H 2 IMes=1,3‐bis(2,4,6‐trimethylphenyl)imidazolidin‐2‐ylidene) in the presence of a terminal alkyne (phenylacetylene) were studied theoretically. The ruthenium η 3 ‐vinylcarbene complex is the most probable product of the reaction between the 14‐electron ruthenium alkylidene species and phenylacetylene. Its subsequent transformation into the ruthenium vinylidene complex and stilbene, both being experimentally observed earlier, is possible. The former is believed to be the active species catalyzing the dimerization of terminal alkynes. The calculated pathway also predicts the formation of [RuCl 2 (H 2 IMes)] species, which might initiate the cyclotrimerization of terminal alkynes or transform into the experimentally detected [RuCl 2 (3‐Br‐py) 3 (H 2 IMes)] complex. An alternative mechanism of the Grubbs catalyst decomposition through an intermediate Ru species having alkylidene and vinylidene ligands in the coordination sphere of ruthenium is also proposed.