Thallium complexes sulfides

Fig. II.8.1 Anodic differential pulse voltammograms obtained after a preliminary reduction of complex sulfides at —1.0 V vs. Ag/AgCl for 60 s. The electrolyte solution was 1 M HCl with 10 M HgCl2. The mercury salt was used to simultaneously plate metallic mercury where the tin and thallium metals could dissolve (reprinted with permission from [14])...

Oxidative phenolic coupling. Biosynthesis of the alkaloid narwedine (3) is known to involve oxidative phenolic coupling of norbelladine derivatives (1), but the usual oxidants for such coupling in vitro convert 1(R = H) into the oxomaritidine skeleton (4) rather than 3. A new biomimetic synthesis of 3 involves the palladacycle 2, formed by reaction of 1(R = CH3) with Li2PdCl4, which is known to form complexes with allylic amines or sulfides (8,176-177). Oxidation of 2 with thallium(III) trifluoroacetate effects the desired coupling to give 3. 

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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