Chalcogen bonding in the solid-state structures of 1,3-bis(benzimidazoliumyl)benzene-based chalcogen-bonding donors

Abstract

1,3-Bis(benzimidazoliumyl)benzene-based chalcogen-bonding catalysts were previously successfully applied in different benchmark reactions. In one of those examples, i.e. the activation of quinolines, sulfur- and selenium-based chalcogen-bonding catalysts showed comparable properties, which is unexpected, as the selenium-containing catalysts should show superior catalytic properties due to the increased polarizability of selenium compared to sulfur. Herein, we present four crystal structures of the respective 1,3-bis(benzimidazoliumyl)benzene-based chalcogen-bonding catalyst containing sulfur (3S ) and selenium (3Se , three forms) as Lewis acidic centres. The sulfur-containing catalyst shows weaker chalcogen bonding compared to its selenium analogue, as well as anion–π interactions. The selenium-based analogues, on the other hand, show stronger chalcogen-bonding motifs compared to the sulfur equivalent, depending on the crystallization conditions, but in every case, the intermolecular interactions are comparable in strength. Other interactions, such as hydrogen bonding and anion–π, were also observed, but in the latter case, the interaction distances are longer compared to those of the sulfur-based equivalent. The solid-state structures could not further explain the high catalytic activity of the sulfur-containing catalysts. Therefore, a comparison of their σ-hole depths from density functional theory (DFT) gas-phase calculations was performed, which are again in line with the previously found properties in the solid-state structures.

Halogen bonds, chalcogen bonds, pnictogen bonds, tetrel bonds and other σ-hole interactions: a snapshot of current progress

“…4) and reflect the growing importance and interest in this class of interactions, alongside the more extensively studied halogen bond. Huber and co-workers report the synthesis and crystal structures of a set of four 1,3-bis(benzimidazoliumyl)benzenebased compounds designed for two-point binding of suitable Lewis bases via chalcogen bonds (Steinke et al, 2023). This class of compounds and related triazolium analogues have been used successfully as Lewis acid catalysts (with chalcogens Ch = S, Se or Te) in several benchmark reactions (Wonner et al, 2017(Wonner et al, , 2019a.…”

Impact of tellurium as an anion dopant on the photovoltaic performance of wide-bandgap Cu(In,Ga)Se2 thin-film solar cells with rubidium fluoride post-deposition treatment

“…Another promising approach for control of the bandgap is to use tellurium (Te) as an anion dopant, leading to a wider distribution of anisotropic electrons and thus an enlarged electropositive region via increase in the strength of the chalcogen bond, as a result of the lower electronegativity and higher radius compared to those of Se and S (Rosenfield et al, 1977;Sönmezoğlu, 2014;Akın et al, 2017;Steinke et al, 2023). Another outstanding property is that Te has a lower effective mass (0.45 m o ) than selenium (1.40m o ), which implies an increase in mobility of the hole carriers of absorber materials (Caldwell and Fan, 1959;Beyer et al, 1971;Madelung, 2012;Sönmezoğlu et al, 2013;Sönmezoğlu and Akman, 2014).…”