Organothallium chemistry

: Organothallium(I) compounds remain obscure and limited in scope. Attempts to generate the simple compound phenylthallium result in disproportionation, giving thallium(III) derivatives: : 3 TlCl + 3 LiPh → TlPh3 + 3 LiCl + 2 Tl Contrariwise, bulky tris(trimethylsilyl)methylthallium forms a stable tetramer, and bulky arylthallium(I) compounds also exist. A well-known organothallium(I) species is thallium cyclopentadienide. It arises by treatment of thallium(I) salts, such as thallium sulfate, with cyclopentadiene. Thallium(I) cyclopentadienide adopts a zig-zag chain structure of cyclopentadienide and thallium. ==Organothallium(III) chemistry==

Trialkyl compounds In the gas and liquid phase, trialkyl organothallium compounds are monomeric and planar. In the solid phase, there is significant intermolecular interactions between the monomers. Trimethyl thallium can be prepared from methyl iodide, methyl lithium, and thallium(I) iodide. Dialkyl compounds Dialkylthallium(III) compounds are ionic salts. They are water soluble and the hydroxide is strongly basic. The cations are linear, resembling isoelectronic dialkylmercury compounds. However, dimeric or polymeric structures may exist in apolar solvents or crystals. R2TlX can be prepared from stoichiometric proportions of Grignard reagents and thallium trihalides, or trialkylthalliums and a hydrohalic acid. Excess boronic acid will result in diarylthallium chloride formation. Phenylthallium dihalides are Lewis acidic in nature, and tend to eliminating the corresponding halobenzene. They grow less stable from down the period, and the diiodide is unknown. Nucleophiles can displace the halide atom, and disproportionation to thallium(III) halides and diphenylthallium halides is also possible. The dichloride transmetallates onto mercuric chloride. ==History==

The first organothallium compound, diethylthallium chloride, was prepared in 1870, shortly after the discovery of the element thallium. ==See also==