Alkylidyne-carbonyl coupling reactions

Templeton and co-workers used the alkylidyne-carbonyl coupling reaction shown in Eq. (156) for the synthesis of the asymmetric alkyne com-... 

Additional examples of nucleophile-induced alkylidyne-carbonyl coupling reactions have been described in recent reviews " photoinduction of such coupling has also been reported. ... 

All expamples of photo-induced alkylidyne-carbonyl coupling reported in the literature to this date involve systems with aryl substituents on the alkylidyne carbon atom. Some results even suggested that this type of coupling reaction may not be viable with alkyl-... 

Ynolate (or ketenyl) ligands RCCO in organometallic chemistry have become easily accessible by the coupling of alkylidyne and carbonyl ligands ". The first coupling of this type was reported in 1976 in the reaction of tungsten alkylidyne-carbonyl complex 31 with trimethylphosphine leading to ynolate complex 32 (equation 21) ... 

C. M. Bastos, "Coupling Reactions of Alkylidyne Ligands with Carbonyl, Isocyanide, and Alkylidyne Ligands on Tungsten", Ph. D. Thesis. State University of New York at Stony Brook, 1991. 

Knox and co-workers synthesized a triruthenium cluster by the reaction of the coordinatively unsaturatcd diruthenium alkyne complex (CpRu)2(/r-CO)(/r-RCCR) 39 with a monometallic carbonyl complex M(CO)4(L) (M = Fe, Ru). Two isomers, 40 and 41, were formed in the reaction of 39 with Ru(CO)4(CH2 = CH2) (Equation (13)). The ratio between 40 and 41 was shown to be dependent on the nature of the substituents of the alkyne. In the case of diphenylacetylene complex, coalescence of the H signals of these isomers, 40a and 41a, was observed. This shows that isomerization between the two isomers took place at considerable rate. In contrast, the reaction of 39 with Fe(CO)4(thf) exclusively afforded a 3- ( )-alkyne complex, in which the alkyne moiety was 7r-coordinated to an iron center. Knox and co-workers also reported the syntheses of triruthenium /i3-alkylidyne complexes by the photolysis of a bimetallic /r-alkylidene complex and a bimetallic diruthenacy-clopentenone complex. In these reactions, formation of the triruthenium frameworks was rationalized by the coupling reaction of the monometallic coordinatively unsaturated species generated by the photolysis with the starting bimetallic complexes. 

A f/oro-mthenacyclopentadiene complex 55 was obtained by the reaction of 7 with linear alkanes (Equation (18))." During this reaction, six C-H bonds of alkane were successively cleaved. Such multiple C-H bond cleavage was rationalized by the cooperative action of the neighboring ruthenium centers of the ttimetallic framework, which promotes the incorporation of alkane into the reaction field of the cluster. Such closo-typc metallacyclopentadiene complexes have been intensively studied using carbonyl clusters, and often prepared by the coupling reaction between the two alkyne ligands of the bis(/r3-7 ( )-alkyne) complex, so-called violet isomer.The /i3-sulfido complex 9 obtained by the reaction of 7 with thiophenol also reacts with alkane to yield a /ts-alkylidyne complex. ... 

Kreissl and co-workers showed that the outcome of the reaction of alkylidyne complexes such as 188 with trimethylphosphine strongly depends on the reaction conditions (169). Whereas at low temperatures in CH2CI2 formation of ketenyl complexes is observed, at room temperature in pentane a significant amount of CO substitution product is obtained [Eq. (152)]. The trimethylphosphine-substituted complexes 189 react with carbon monoxide to form -ketenyl complexes. A very similar result was obtained by Stone and co-workers in the reaction of complex 190 with PMes in petroleum ether at room temperature [Eq. (153)] (35). A mixture of carbonyl substitution product and coupling product was isolated. Reac-... 

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