4-Tetrafluoropyridyl Silver(I), AgC5F4N, in Redox Transmetalations with Selenium and Tellurium

Se­(C5F4N)2 and Te­(C5F4N)2 were prepared via redox transmetalations of AgC5F4N and the corresponding elements in good yields. The crystal structures of both derivatives exhibit infinite chains caused by a weak intermolecular contact between the chalcogen and one nitrogen atom with a T-shaped (ψ-pentagonal-bipyramidal) ligand arrangement. Crystallization of both reagents from dimethylsulfoxide gave single crystals of the corresponding 1:1 adducts that crystallize in infinite chains best expressed by the formula [E­(C5F4N)2·(μ-DMSO)]∞ (E = Se, Te). In these cases, the coordination spheres of selenium and tellurium are square-planar (ψ-octahedral). Similar effects are found in the molecular structures of [Te­(C5F4N)2·TMTU]∞ and [Te­(C6F5)2·TMTU]∞ (TMTU = tetramethylthiourea). Differences in the Te–S interatomic distances clearly indicate the C5F4N ligand being significantly more electron-withdrawing in comparison with the C6F5 group; that is, Te­(C5F4N)2 is the stronger Lewis acid.