Heterovalent chalcogen bonding: supramolecular assembly driven by the occurrence of a tellurium(ii)⋯Ch(i) (Ch = S, Se, Te) linkage

The dichalcogenides Ph₂Ch₂ (Ch = S, Se, Te) were cocrystallized with perfluorinated chalcogen bond donors Tol^F₂Te and Py^F₂Te (Tol^F = 4-CF₃C₆F₄, Py^F = 4-NC₅F₄) to obtain the 1 : 1 cocrystals Tol^F₂Te·Ph₂Ch₂ (Ch = S 1, Se 2, Te 3) and Py^F₂Te·Ph₂Se₂ (4). In the X-ray structures of 1-4, heterovalent Te^II⋯Ch^I (Ch = S, Se, Te) chalcogen bonding was identified on consideration of the geometrical parameters and, in addition, based on the results of appropriate density functional theory (DFT) calculations including quantum theory of atoms-in-molecules (QTAIM), noncovalent interaction plot (NCIplot) analysis, molecular electrostatic potential surfaces (MEP), and atoms-in-molecules (AIM) charge analysis. The binding energy in the dimeric structure is in the range between −9.7 and −12.9 kcal mol⁻¹, where the contribution of the heterovalent chalcogen bonding ranges from −4.7 to −6.5 kcal mol⁻¹. In the Te^II⋯Ch^I moiety, the Te^II center plays the role of an electrophilic partner, while the chalcogens in the lower oxidation state, 1+, exhibit nucleophilic properties. The heterovalent Te^II⋯Ch^I (Ch = Se, Te) chalcogen bonding was thus used for the targeted noncovalent integration of two Ch centers in different oxidation states.