4-Tetrafluoropyridyl Silver(I),
AgC<sub>5</sub>F<sub>4</sub>N, in Redox Transmetalations with Selenium
and Tellurium
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Abstract
Se(C<sub>5</sub>F<sub>4</sub>N)<sub>2</sub> and Te(C<sub>5</sub>F<sub>4</sub>N)<sub>2</sub> were prepared via redox transmetalations
of AgC<sub>5</sub>F<sub>4</sub>N 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(C<sub>5</sub>F<sub>4</sub>N)<sub>2</sub>·(μ-DMSO)]<sub>∞</sub> (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(C<sub>5</sub>F<sub>4</sub>N)<sub>2</sub>·TMTU]<sub>∞</sub> and [Te(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>·TMTU]<sub>∞</sub> (TMTU =
tetramethylthiourea). Differences in the Te–S interatomic distances
clearly indicate the C<sub>5</sub>F<sub>4</sub>N ligand being significantly
more electron-withdrawing in comparison with the C<sub>6</sub>F<sub>5</sub> group; that is, Te(C<sub>5</sub>F<sub>4</sub>N)<sub>2</sub> is the stronger Lewis acid