New aspects in the chemistry of aromatic and fluoroaromatic selenium and tellurium compounds: Similarities and diversities

Polyfluorinated aromatic selenium and tellurium compounds are synthesized a nd their chemistry and properties discussed. Besides the standard character ization by spectroscopic methods. several crystal structures were obtained. Improved syntheses for the starting materials were presented for the known (C6F5Se)(2) (1), C6F5SeCl (2), (C6F5)(2)Se (3), (C6F5)(2)Te (4a) and new ( R-F)(2)Te (4b-d, R-F = 4-CF3C6F4, 2,6-C6F2H3 and 4'-(4-CF3C6F4O)C6F4). Some chemistry of the corresponding Se/Te(IV) derivatives, obtained by oxidatio n of 3 and 4, as well is nucleophilic substitution reactions of 2 is descri bed with a particular focus on pseudohalide species. An unusual perfluoroph enyl migration is observed for the reaction of diaryltellurium(IV) dihalide (Cl, Br) with cyanide leading to triaryltelluronium chloride/bromide. The synthesis and thorough characterization of the first diaryltellurium(IV) di azides is presented.