Heterovalent chalcogen bonding: supramolecular assembly driven by the occurrence of a tellurium (II)center dot center dot center dot Ch(I) (Ch = S, Se, Te) linkage

The dichalcogenides Ph(2)Ch(2) (Ch = S, Se, Te) were cocrystallized with perfluorinated chalcogen bond donors Tol(2)(F)Te and (Py2Te)-Te-F (Tol(F) = 4-CF3C6F4, Py-F = 4-NC5F4) to obtain the 1:1 cocrystals Tol(F)(2)Te center dot Ph(2)Ch(2) (Ch = S 1, Se 2, Te 3) and (PyFTe)-Te-2 center dot Ph2Se2 (4). In the X-ray structures of 1-4, heterovalent Tell (Ch = S, Se, Te) chalcogen bonding was identified on consideration of the geometrical para meters 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 center dot center dot center dot 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 center dot center dot center dot Ch(I) (Ch = Se, Te) chalcogen bonding was thus used for the targeted noncovalent integration of two Ch centers in different oxidation states.