Other Organothalliums

In contrast to other organothallium(I) compounds, cyclopentadienyl-thallium(I) is a remarkably stable compound. Samples can be stored in sealed bottles for months without appreciable decomposition occurring it is unaffected by water and dilute alkali and it is only slowly oxidized by air at room temperature. Cyclopentadienyltballium(I) was first prepared by Meister in 1956 by addition of freshly distilled cyclopentadiene to a suspension of thallium(I) sulfate in dilute potassium hydroxide solution 101, 102). A number of variations of this procedure have been described (5, 25, 34, 56), and the compound has been made in other ways 35, 56,110, 164), but Meister s preparation, in which the yield of crude product is greater than 90%, remains the method of choice. Purification of crude cyclopenta-dienylthallium(I) is best accomplished by vacuum sublimation, and purity of samples can readily be assessed by gas-liquid chromatography on silicone oil at 170° C using hydrogen as carrier gas (7). 

There is some evidence for the formation of T13+/CN- complexes in aqueous solution,373 but no synthetic study of thallium(III) with this or other group IV ligands has apparently been reported, although the [T1(CN)4] anion is known in T1(CN)2 cf. Section 25.2.7). Organothallium(III) compounds are of course well known.272... 

The ligand coupling and ligand transfer mechanisms explain a number of transformations of organothallium compounds. The best studied reaction is the carbon-iodine conversion for the synthesis of aryl iodides, but other efficient conversions have been also described. 

There is also a lot of structural information for other thallium(III) compounds (e.g., organothallium compounds), which has been obtained from the spin-spin coupling pattern of their NMR spectra. However, no interatomic distances have been obtained in this way. 

Relevant to the preparation of organothallium compounds and disproportionation it is appropriate to mention here some novel syntheses involving organothallium and some other organometallic compounds. We prepared trimethylthallium in essentially quantitative yields by three different procedures. One of these was the following ... 

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