Methylidynetricobalt nonacarbonyl

Another synthesis of aryl-substituted methylidynetricobalt nonacar-bonyls was developed by Dolby and Robinson (15) who found that chloro-methylidynetricobalt nonacarbonyl alkylate s aromatic compounds in a Friedel-Crafts-type reaction. High product yields were obtained when equimolar amounts of ClCCo3(CO)9 and aluminum chloride and an excess of the arene were stirred at 60°-70°C for 2 hours. When the arene was a solid, the reaction was carried out in dichloromethanc solution. Both ortho and para substitution was encountered, the size of the substituent (s) already present on the benzene ring appearing to determine the position of substitution (Table IV). Noteworthy is that milder temperature conditions affected the position of substitution thus, reaction of chlorobenzene with chloromethylidynetricobalt nonacarbonyl in dichloromethane at 42° gave... 

At the time the chemistry of (OC)9Co3CCO+PF6 was being developed (27, SO), another route to this novel acylium ion was found in these laboratories (31, 32). This discovery was a result of our intention to adapt the Friedel-Crafts synthesis of benzylidynetricobalt nonacarbonyl complexes of Dolby and Robinson (15) to the preparation of alkyl derivatives of methylidynetricobalt nonacarbonyl, whose general preparation was not well in hand. The reaction chosen for investigation was the aluminum chloride-induced interaction of tetraalkyltin compounds with ClCCo3(CO)9 In analogy to a known ketone synthesis (33),... 

Other reports include reactions in supercritical ethylene, promotion by molecular sieves, and the effect of a phosphine sulfide. Clusters such as methylidynetricobalt nonacarbonyl are also effective catalyst of the Pauson-Khand reaction." Vinyl esters are identified as surrogates for ethylene. ... 

The interconversions of such methylidynetricobalt nonacarbonyl complexes obtained by the direct, Co2(CO)8-based routes, particularly, HCCo-(00)9 [prepared by reaction of bromoform with Co2(CO)s] and XCC03-(00)9 (X = Cl, Br, I), provide a second route to many RCC03 (CO)9 compounds where R can be an alkyl, an aryl, a vinyl, an organofunctional, or a silyl group. The following equations illustrate the types of such reactions which have been reported. 

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