Carbyne complex iridium

Carbene and Carbyne Complexes of Ruthenium, Osmium, and Iridium... 

When the reaction was attempted with Cl2C=IrCl3(PPh3)2 a crystalline solid, which was a green color typical of osmium carbyne complexes, could be observed at -78°C, but attempts to characterize this solid at room temperature were unsuccessful (39). No well-defined carbyne complexes of iridium have been reported to date. 

Iridium-carbon multiple bonds allenylidene complexes, 7, 355 carbene complexes, 7, 344 carbyne complexes, 7, 361 higher cumulenylidene complexes, 7, 358 vinylidene complexes, 7, 352 Iridium-carbon single-bonded complexes alkenyl complexes, 7, 319 alkyl and aryl complexes, 7, 303 in C-C bond-forming catalysis, 7, 335 characteristics, 7, 303... 

IRIDIUM CARBENE AND CARBYNE (See Carbyne Complexes) COMPLEXES ... 

The chemistry of metal-carbon triple bonds has developed considerably during the late 1980s. The synthetic basis was broadened, the utility of high-valent metal alkylidynes in metathesis reactions was further developed and refined, and the potential of low-valent carbyne complexes for applications in organic synthesis has become more apparent. The discovery of novel iridium alkylidyne complexes indicates that the full range of metal-carbon triple bonds is not yet known. We can therefore expect that future work in this area of organometallic chemistry will lead to new discoveries with fundamental implications and practical applications. 

The basicity at the 3-carbon is illustrated by the reactions in Equations 13.26 and 13.27. Reaction of the octahedral rhenium vinylidene in Equation 13.26 with HBF generates the cationic carbyne complex from addition of a proton to the basic 3-carbon. Because low-valent metals are often basic, addition of a proton to the vinylidene 3-carbon is likely to occur by a multi-step process initiated by protonation of the metal center. This initial protonation at the metal center would then be followed by migration of the proton to the 3-carbon. The reaction of acid with the iridium vinylidene in Equation 13.27 illustrates this mechanism. In this case, protonation first generates an iridium-hydride complex. The hydride in this complex tlien migrates to the p-carbon to generate an alkylidyne complex. ... 

September 1985) have been published. The 300th volume of J. Organomet. Chem. is commemorated by a number of reviews by well-known organometallic chemists many of these reviews are of relevance to this chapter. Carbene and carbyne complexes of ruthenium, osmium, and iridium,and the role of electrophilic metal carbenes as reaction intermediates in catalytic reactions, have been reviewed. The reactivity of the ions Ru", Rh", and Pd with alkanes in the gas phase has been shown to be markedly different to that of their first row congeners. 

A. Hohn, and H. Werner, Carbyne-Iridium Complexes Evidence for an Equilibrium Between Alkenylidene(hydrido) and Carbyne Isomers, Angew. Chem. Int. Ed. Engl. 25, 737-738 (1986). 

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