Thallium, organo- compounds

Thallium(III) compounds dominate the known organo-metallic chemistry of thallium. The structural chemistry organothallium(III) compounds has been reviewed. ... 

It will be seen that a number of tlie reactions afford means of obtaining organo-tballium derivatives. In the case of organo compounds of the elements of Group V., it may be stated that phosphorus and antimony chlorides yield no organo-thallium derivatives, whereas arsenic and bismuth chlorides are capable of yielding eompoimds of the type... 

In a first approximation supra-Cp metal complexes can be prepared the same way as normal or other Cp-metal and organo-metal bonds in general. The methods used most often (see Appendix) are the metathesis reaction [Eq. (1)] followed in number by oxidative additions (Eq. (2)] and metallation/deprotonation reactions [Eq. (3)]. The latter is especially important for the cyclpentadienyl alkali metal compounds. A useful variation of reaction (3) is the formation of CpTl in an acid/base reaction from cyclopentadiene and thallium ethoxide [Eq. (3b)]. This represents a convenient route to cyclopentadienylthallium compounds, which are also valued (in place of Cp alkalis) as mild Cp-transfer reagents for the synthesis of difficultly isolable cyclopentadienyl derivatives (77). 

The metals of the aluminium sub-group are permanent in the air at ordinary temperatures, but when heated in oxygen or the air they become coated with their oxide. The volatility of the metals increases with the atomic weights, and the heavier metals are more easily reduced than those of lower atomic weight. The metals are all malleable, fusible, have small atomic volumes and form hydroxides, M(OH)3, which are typically amphoteric in the first three elements of the sub-group and basic only in the case of thallium. The last four members of the family form alums, and both aluminium and thallium form organo-metallic compounds, resembling zinc in this respect. 

The mixture of double bond isomers of l,2,3,4-tetramethyl-5-(trifluoro-methyl)cyclopentadiene (Cp H) is a clear, colorless liquid with a sweet ole-finic odor similar to that of pentamethylcyclopentadiene. Cp H is an air-stable compound but it should be stored in the refrigerator. Although gas chromatographic analysis shows two peaks, the presence of all three of the possible cyclopentadiene isomers is indicated by H NMR spectroscopy as three quartets for the ring protons are observed at 3.26 (Jhf = 10.0 Hz), 2.99 (Jhh = 6.7 Hz), and 2.66 ppm (Jhh = 6.8 Hz) with a relative ratio of approximately 1 16 2.4 for isomers I, II, and III, respectively. Resonances between 4.8 and 5.0 ppm are attributed to products that result from an elimination mechanism rather than cyclization in the last step of the synthesis. These impurities boil very close to that of Cp H, but they are removed by careful fractional vacuum distillation as part of the forerun. The IR spectrum (neat liquid) exhibits significant bands at 2977(vs), 2937(vs), 2884(s), 2864(s), 2751(w), 1658(m), 1599(s), 1446(s), 1384(vs), 1357(vs), 1280(s), 1258(vs), 1164(vs), 1099(vs), 1012(vs), and 686(m) cm . The syntheses of organotransi-tion metal complexes are usually carried out with the 91% purity Cp H product. Because alkali metal and thallium salts of Cp are unstable, organo-transition metal complexes are prepared from Cp H itself, as are many complexes of pentamethylcyclopentadiene and cyclopentadiene."... 

Like Grignard compounds, the REM halide/carbonylmetals easily react with organo-halides or metal halides as well as with thallium and alkali metal derivatives, for example [48] ... 

Rapid intermolecular exchange of groups is also occurring in organo-thallium compounds at room temperature, since metal-proton spin-spin... 

McKillop A, Taylor EC. Compounds of thallium in organic synthesis. In Wilkinson G, editor. Comprehensive organo-metallic chemistry. Vol. 7. New York Pergamon Press Ltd. 1982 p 465-513. 

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