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Ruthenium−Acetylide-Mediated Catalytic Dimerization of RC⋮CH (R = Ph, CO2Me) and the Formation of the New Ruthenium η3-Butadienyl Complex C5Me5Ru(PPh3)[η3-PhCHCHCC(Ph)C⋮CCPh]

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journal contribution
posted on 02.09.1997, 00:00 by Chae S. Yi, Nianhong Liu, Arnold L. Rheingold, Louise M. Liable-Sands
The in-situ-generated ruthenium−acetylide species C5Me5Ru(PPh3)C⋮CPh (1) was found to catalyze the dimerization of RC⋮CH to give predominantly the head-to-head dimers trans-RCHCHC⋮CR (R = Ph (3), TON = 607 h-1; R = CO2Me (4), TON = 975 h-1). A new ruthenium η3-butadienyl complex C5Me5Ru(PPh3)(η3-PhCHCHCC(Ph)C⋮CPh) (5) was isolated at the end of the catalytic dimerization of PhC⋮CH (81% based on Ru). The structure of the 1.5 benzene-solvated complex 5·1.5C6H6 was established by X-ray crystallography. Complex 5 was independently prepared from the stoichiometric reaction of C5Me5Ru(PPh3)(Cl)CCHPh (2) with the dimer 3 in the presence of NEt3. The formation of an intermediate η2-alkyne complex C5Me5Ru(PPh3)(η2-PhCHCHC⋮CPh)(C⋮CPh) (6) was observed during the reaction.