Robust S₄⋅⋅⋅O Supramolecular Synthons: Structures of Radical‐Radical Cocrystals [p‐XC₆F₄CNSSN]₂[TEMPO] (X=F, Cl, Br, I, CN).

Stephaniuk, Nadia T.; Nascimento, Mitchell A.; Nikoo, Sahar; Heyer, Elodie; Watanabe, Lara K.; Rawson, Jeremy M.

Cocrystallization of the dithiadiazolyl (DTDA) radicals p‐XC6F4CNSSN (X=F, Cl, Br, I, CN) with TEMPO afforded the 2 : 1 cocrystals [p‐XC6F4CNSSN]2[TEMPO] (1–5) whose structures all reflect a common S4⋅⋅⋅O supramolecular motif. The nature of this interaction was probed by DFT calculations (M06/aug‐cc‐pVDZ) on 1 which revealed that the enthalpy of formation of the [C6F5CNSSN]2[TEMPO] supramolecular motif from [C6F5CNSSN]2 and TEMPO is substantial (−54.0 kJ mol−1). Electronic structure calculations revealed a TEMPO‐based doublet S=1/2 configuration as the ground state with limited spin density on the DTDA rings (2.4 %). The corresponding spin quartet state is +78.9 kJ mol−1 higher in energy. An atoms‐in‐molecules analysis reveals four bond critical points (BCPs) between the TEMPO O and the DTDA S atoms as well as additional BCPs between selected DTDA S atoms and methyl H atoms of the TEMPO molecule. Herein, the structures of 2–5 are considered within the context of a hierarchical view of competing and complementary intermolecular interactions; in particular, the established supramolecular CN⋅⋅⋅S−S synthon is sacrificed in order to form the new S4⋅⋅⋅O interaction.

HEAT of formation; BROMINE; INTERMOLECULAR interactions; ELECTRONIC structure; ATOMS

Chemistry - A European Journal, 2022, Vol 28, Issue 15, p1

0947-6539

Academic Journal

10.1002/chem.202103846