Various Sorts of Chalcogen Bonds Formed by an Aromatic System

Abstract

The chalcogen Y atom in the aromatic ring of thiophene and its derivatives YC4H4 (Y = S, Se, Te) can engage in a number of different interactions with another such unit within the homodimer. Quantum calculations show that the two rings can be oriented perpendicular to one another in a T-shaped dimer in which the Y atom accepts electron density from the π-system of the other unit in a Y···π chalcogen bond (ChB). This geometry best takes advantage of attractions between the electrostatic potentials surrounding the two monomers. There are two other geometries in which the two Y atoms engage in a ChB with one another. However, instead of a simple interaction between a σ-hole on one Y and the lone pair of its neighbor, the interaction is better described as a pair of symmetrically equivalent Y···Y interactions, in which charge is transferred in both directions simultaneously, thereby effectively doubling the strength of the bond. These geometries differ from what might be expected based simply on the juxtaposition of the electrostatic potentials of the two monomers.

Adjusting the balance between hydrogen and chalcogen bonds

“…Numerous past calculations of related systems have confirmed the dependability and accuracy of this combined approach. 15,58,67,71,[76][77][78][79][80][81][82] The aug-cc-pVDZ-PP pseudopotential 83 was applied to fourth-row Te as it takes into account certain relativistic effects. The larger triple-z aug-cc-pVTZ set was used to compute specialized electronic parameters, such as charge transfers, NBO, and AIM properties, along with the all-electron cc-pVTZ-DK3 basis for Te.…”

“…The (ChN) 2 square bonding motif of chalcogenadiazole dimers that contains a pair of ChBs was the subject of recent quantum chemical analyses and the various geometric dispositions in which two related molecules can pair up was probed as well. 67 The placement of halogen atoms on chalcogenadiazoles enable elucidation of the factors involved in the competition between a XB and ChB. 59 The strength of the HB was also thrown into the mix with the other two 68 for a series of 1,3,4-chalcogenadiazoles.…”

Supramolecular architectures featuring Se⋯N secondary-bonding interactions in crystals of selenium-rich molecules: a comparison with their congeners

“…Not surprisingly, theoretical aspects and the energetics of chalcogen-bonding have attracted the interest of computational chemists in recent years. 50–57…”

“…Not surprisingly, theoretical aspects and the energetics of chalcogen-bonding have attracted the interest of computational chemists in recent years. [50][51][52][53][54][55][56][57] Recent, comparative studies on the model homo-dimer comprising two five-membered chalcogen-substituted adiazolyl rings connected by two Ch⋯N interactions, i.e. via a four-membered {⋯Ch-N} 2 synthon, for Ch = O, S, Se and Te, are especially worth highlighting.…”

Properties and Stabilities of Cyclic and Open Chains of Halogen Bonds

“…The latter are characterized by the replacement of the bridging proton by any of a wide assortment of other atoms, most more electronegative than H. These interactions are commonly categorized in reference to the family of elements from which this replacement bridging atom is drawn. The chalcogen bond, − for example, makes use of S, Se, and Te, while the involvement of P, As, or Sb leads to the designation as a pnicogen bond. − …”