Ruthenium allenylidene salt

The effective RCM of dienes, catalyzed by ruthenium allenylidene salts [Cl(PCy3)(p-cymene) Ru(=C=C=CPh2)]+(0CF3S02), has been observed in ionic liquid (l-butyl-3-methylimidazolium salts) (Eq. 80) [133]. 

An alternative solution to ionic tagging to confine a catalyst into an IL phase is that of using a cationic metathesis complex, e.g. ruthenium allenylidene salt (86). Treatment of diallyltosylamide at 80 °C for 5h dissolved in [bmi-m][OTf] in the presence of 2.5 mol.% of pre-catalyst 86 led to the... 

S meril, D. Olivier-Bourbigou. H. Bruneau, C. Dixneuf, P.H. Alkene metathesis catalysis in ionic liquids with ruthenium allenylidene salts. Chem. Commun. 2002. 146-147. 

The synthesis of the first ruthenium indenylidene catalysts arose from a 1998 report by the Fiirtsner and Dixneuf groups [13] that identified ruthenium-allenylidene complexes, easily prepared by the activation and dehydration of propargylic alcohols, as efficient catalysts for RCM reactions. These catalyst precursors were made from readily available arene-ruthenium(II) complexes containing a bulky and electron-donating ligand in the presence of the non- or weakly coordinating anion salt NaX or AgX (Scheme 14.1). 

The use of Me3NO to induce substitution of dppm (bis(diphenylphosphino)-methane) for CO molecules on dinuclear iron complexes led to insertion of CO into C-C bonds of alkyne-derived metallacycles. Similar behavior was observed when [PPNJCl salts were used to favor the formation of alkyne-substituted triruthenium dppm-containing clusters.I This behavior should be compared with the insertion of CO into allenylidene and phosphido-bridging ligands occurring when dppm coordinates to binuclear ruthenium complexes as shown in Fig. 3. This reaction is a nucleophilic attack of the coordinated allenylidene and phosphido groups on a coordinated CO (see Section 2.8.2.2). 

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