Deciphering the Role of Noncovalent Interactions in the Conformations of Dibenzo‐1,5‐dichalcogenocines

Abstract

This work reports a combined experimental and theoretical study on the new dibenzo‐1,5‐ditellurocine 2‐Te in order to get an overview on the parameters controlling conformational change and to explain the differences with sulfur and selenium analogues. The preference of the boat conformer over the chair one is revealed by DFT calculations. For 2‐Te, a ΔG value of about 3 kJ/mol was calculated, close to the value measured by NMR (5 kJ/mol). However, DFT calculations with implicit solvation effects could not clearly establish the presence of an intramolecular Te…HC noncovalent interaction (NCI), as observed in the solid state. The Independent Gradient Model (IGM) methodology discloses an existent but probably not sufficiently discriminating Te…HC NCI. It also confirms that van der Waals interactions between phenyl rings is a source of stabilization of the boat conformer. Furthermore, electrostatic potential analysis suggests that chalcogen bonds between Te σ‐holes and solvent might play an important role.

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

“…As we recently demonstrated that chlorinated solvents clearly interact in solution with Te σ‐holes, [12] we performed similar experiments with less competitive solvents than CDCl 3 , i. e. toluene‐ d8 and cyclohexane‐ d12 . In order to increase the strength of the Te⋅⋅⋅O interaction, a stronger σ‐hole acceptor (Et 3 PO [36] ) was also used.…”

“…Based on such considerations, we are thus conducting detailed investigations of selected organotellurium compounds in order to tune σ‐hole deepness and look at the resulting interactions, [12] in the solid state but mostly in solution, with the aim to apply them to catalysis [11e] . For the present study, we selected diaryl ditellurides where each tellurium atom possesses two σ‐holes at the antipode of C−Te (σ Te‐C ) and Te−Te (σ Te‐Te ) bonds (Figure 1B).…”

Cover Feature: Chalcogen Bonding with Diaryl Ditellurides: Evidence from Solid State and Solution Studies. (Chem. Eur. J. 25/2022)

“…As we recently demonstrated that chlorinated solvents clearly interact in solution with Te holes, [12] we performed similar experiments with less competitive solvents than CDCl3, i.e. toluene-d8 and cyclohexane-d12.…”

“…Based on such considerations, we are thus conducting detailed investigations of selected organotellurium compounds in order to tune -hole deepness and look at the resulting interactions [12] , in the solid state but mostly in solution, with the aim to apply them to catalysis. [11e] For the present study, we selected diaryl ditellurides where each tellurium atom possesses two -holes at the antipode of C-Te (Te-C) and Te-Te (Te-Te) bonds (Figure 1B).…”

Hydrogen bonding with polonium

“…Moreover, Weiss et al observed that the boat conformer of dibenzo-1,5-ditellurocine is more stable than the chair conformer. Their analysis reveals the presence of an interaction between Te and C-H. 26 It is noteworthy that although there are reports on H-bonds involving heavier chalcogen atoms, polonium still remains unexplored. Polonium is a naturally occurring radioactive element, and not many molecules containing polonium are known.…”