Thallium complexes, characteristics

The kinetic characteristics of ligand exchange of thallium complexes in solution have been little explored, in contrast to the numerous equilibrium studies (4-6,41,57,61,66,67,90,92,93,96,97,112,214-246) and a large number of studies of redox reactions involving thallium (81, 100, 103, no, 246-288). 

Overall, the UV-visible, NMR, and electrochemical data for the range of O -bonded complexes of gallium, indium, and thallium porphyrins show that there is a trend from pure a -bonded character of the M—C bond in the alkyl complexes to the much more ionic character observed for the fluorophenyl and acetylide complexes. These more ionic complexes show NMR and UV-visible characteristics more like those of the ionic M(Por)Cl or M(Por)C104 complexes. ... 

The indium(II) halides, whose solid state structures are In+[InX4] for X = Br and I (see Section 25.2.2.5), have served as starting points for the preparation of [IntcrownJJpnX X = Cl, Br, I), [In(crown)][AlCl4] and [In(cyclam)][InX4](X = Br, I crown = dibenzo-18-crown-6 cyclam = 1,4,8,11-tetraazacyclotetradecane).24 The characteristic vibrational spectra of the InXj anions were important in establishing the solid state structure of these salts of indium(I) cationic complexes. These macrocydic ligands do not react with suspensions of InX (cf. thallium below). 

The chemical properties span a range similar to the representative elements in the first few rows of the periodic table. Francium and radium are certainly characteristic of alkah and alkaline earth elements. Both Fr and Ra have only one oxidation state in chemical comhina-tions and have little tendency to form complexes. Thallium in the 1+ oxidation state has alkah-like properties, but it does form complexes and has extensive chemistry in its 3+ state. Similarly, lead can have alkaline earth characteristics, hut differs from Ra in forming complexes and having a second, 4+, oxidation state. Bismuth and actinium form 3+ ions in solution and are similar to the lanthanides and heavy (Z > 94) actinides. Thorium also has a relatively simple chemistry, with similarities to zirconium and hafiuum. Protactinium is famous for difficult solution chemistry it tends to hydrolyze and deposit on surfaces unless stabilized (e.g., by > 6 M sulfuric acid). The chemistry of uranium as the uranyl ion is fairly simple, hut... 

As early as the beginning of this century, Abegg and Bodlander pointed out that noble metals (having positive E relative to hydrogen) prefer to form complexes with iodide, sulfide and cyanide, and hence have what Ahrland et al. call B characteristics. For some reason, this is fairly valid, with the striking exception of thallium(I) and (III), and lead(II), where the metallic elements have negative E. Seen from the point of view of complex formation constants (Bjerrum, 1950) and in particular of the influence of substitution of a ligating... 

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