Chalcogen Bonding with Diaryl Ditellurides: Evidence from Solid State and Solution Studies.
R. Weiss, Emmanuel Aubert, Loïc Groslambert, Patrick Pale, Victor Mamane
Abstract
Abstract The chalcogen bonding (ChB) ability of Te is studied in symmetrical diaryl ditellurides ArTeTeAr. Among the two Te σ‐holes, the one along the less polarized Te−Te bond was calculated as the more electropositive. This counter‐intuitive situation is due to the hyperconjugation contribution from Te lone pair to the σ* of the adjacent Te which coincides with σ‐hole along the more polarized Te−Ar bond. ArTeTeAr showed notable structural features in the solid state as a result of intermolecular Te⋅⋅⋅Te ChB, such as a Te 4 rectangle through dimer aggregation or a triangular Te 3 motif, where one Te interacts with both Te atoms of a neighboring molecule through both its σ‐hole and lone pair, in a slightly frustrated geometry. Lewis acidity of ArTeTeAr was also evaluated by NMR with R 3 PO as σ‐hole acceptors in different solvents. Thus, 125 Te NMR allowed monitoring Te⋅⋅⋅O interaction and delivering association constants ( K a ) for 1 : 1 adducts. The highest value of K a =90 M −1 was measured for the adduct between ArTeTeAr bearing CF 3 groups and Et 3 PO in cyclohexane. Notably, by using n Bu 3 PO, Te⋅⋅⋅O interaction was revealed by 19 F‐ 1 H HOESY showing spatial proximity between CF 3 and CH 3 of n Bu 3 PO.