Ruthenium metathesis catalysts exchange

The formation of metal carbenes from sulfonium ylides has been also recently disclosed. Treatment of the sulfonium salt with KHMDS followed by the addition of tris(triphenylphosphine) ruthenium dichloride and phosphine exchange with tricyclohexyl-phosphine led to the formation of the Grubb s metathesis catalyst... 

The induction period of the catalysis involves the replacement of an acetonitrile ligand by silicon hydride followed by o-bonding metathesis reaction, which makes the H-atom exchange of silicon hydride for the Cl-atom of Ru-complex to form [RuH(NCMe)4]+ with the elimination of chlorosilane. The formation of ruthenium hydride catalyst (4) (1) that generates the product is a... 

Ruthenium catalysts, coordinated with an N-heterocyclic carbene allowed for the ROMP of low-strain cyclopentene and substituted cyclopentenes (10,23). Suitable ruthenium and osmium carbene compounds may be synthesized using diazo compounds, by neutral electron donor ligand exchange, by cross metathesis, using acetylene, cumulated olefins, and in an one-pot method using diazo compounds and neutral electron donors (24). The route via diazo compounds is shown in Figure 1.7. 

NMR studies of degenerate ligand exchange in generation I and generation II ruthenium alkylidene pro-catalysts for alkene metathesis... 

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