Indium metal organoindium halides

Another successful synthetic route to indium-metal species is via insertion of organoindium (I) compounds into metal-halide or metal-metal bonds. The organo... 

The coordination chemistry of indium(I) received little or no attention for many years, largely no doubt because of the lack of suitable starting materials. The indium(I) halides can be easily prepared,1 but are intractable materials which readily undergo hydrolysis and disproportionation (but see Section 25.2.2.1). The only known organoindium(I) compounds are the cyclopentadienyl and methycyclopentadienyl derivatives,8 and the former has proven a useful starting point for some synthetic work. Electrochemical methods have been used either to reduce higher states, or to oxidize the metal in the presence of suitable ligands, in order to produce indium(I) species. 

In the past decade much effort in organoindium chemistry has been devoted to study of carbonyl allylation and aUylindation of carbon-carbon multiple bonds with allylic indium reagents. Apart from the conventional transmetalation of allyl-lifhium or aUyl Grignard reagents with indium(III) halides, a method widely used for preparation of allyhndium(III) compounds is the oxidative addition of metallic indium or indium(I) iodide to aUyhc substrates [3, 6]. Transmetalation of allylstan-nane with indium(III) chloride also gives allylindium(III) [7]. Allylindium(I) was recently prepared by transmetalation of allylmercury with metallic indium in water this compound is regarded as an intermediate in the allylation of carbonyl compounds in aqueous media [8]. A new method of preparation of allylic in-dium(III) reagents - reductive transmetalation of a 7r-allylpalladium(ll) complex with indium(I) salts has been reported this enables the use of a wide variety of allylic compounds and solvents [9]. 

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