Chalcogen Bonding with Diaryl Ditellurides: Evidence from Solid State and Solution Studies.

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 TeÀ 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 σhole along the more polarized TeÀ 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 À 1 was measured for the adduct between ArTeTeAr bearing CF 3 groups and Et 3 PO in cyclohexane. Notably, by using nBu 3 PO, Te•••O interaction was revealed by 19 F-1 H HOESY showing spatial proximity between CF 3 and CH 3 of nBu 3 PO.

Hybrid Quinoline Telluroether Ligand Derived Copper and Silver Complexes: Synthesis, Structural and Electronic Properties

“…The intermolecular Te⋅⋅⋅Te interactions is shorter than the sum of the van der Walls radii of tellurium (4.40 Å) and also shorter than the reported values of 3.87(7) Å, [47] and 3.9124(15)–718(16) Å [3] . The intermolecular Te⋅⋅⋅N distance 3.593(3) Å is longer than the interactions observed in previous reports 2.340(3)–2.743(5) Å [46–50] …”

“…[3] The intermolecular Te•••N distance 3.593(3) Å is longer than the interactions observed in previous reports 2.340(3)-2.743(5) Å. [46][47][48][49][50] The corresponding telluroether 3 (Figure 3) has ffTe1À C10À Te2 bond angle 106.6(2)°. Also, the quinoline groups of the asymmetric units of 3 are perpendicular to each other with torsion angles of ffC1À Te1À C10À Te2 and ffC11À Te2À C10À Te1 179.13(2)°and À 79.94(2)°.…”

Chalcogen Bonds: How to Characterize Them in Solution?

“…The strategy of combining XRD, theoretical calculations, 1 H and 125 Te NMR, and 2D NMR also allowed detection of Te…O ChB in solution between diaryl ditellurides and phosphine oxides. [13] ChB between selenonium salts and dimethylacetamide could also be detected through carbonyl and selenium shifts in 13 C and 77 Se NMR. [21] Figure 4.…”

“…Interestingly, such ChB induced conformational preferences have also been developed in molecular balances used to examine and evaluate solvent and substituent effects on ChB. [5d,16] Besides the common 1 H and 13 C NMR, 17 O, 77 Se and 125 Te NMR can be used to identify and study ChB. The main interest of using such Ch nuclei is their direct involvement in ChB, associated with their sensitivity and wide chemical shift range.…”

Adjusting the balance between hydrogen and chalcogen bonds

“…Consequently, chalcogen atoms can bind to one another, forming triangular, square, or even larger Ch n arrangements. [57][58][59][60][61][62] Chalcogenadiazoles hold a special place in the study of ChBs. This sort of molecule places a Ch atom between two N atoms in the context of an aromatic 5-membered ring.…”