Noncovalent Sulfoxide–Nitrile Coupling Involving Four-Center Heteroleptic Dipole–Dipole Interactions between the Sulfinyl and Nitrile Groups
Daniil M. Ivanov, Sergey V. Baykov, Alexander S. Novikov, Г.В. Романенко, Nadezhda A. Bokach, R. A. Évarestov, Vadim Yu. Kukushkin
Abstract
The 4-X-5-nitro substituted phthalodinitriles (X = Br 1, I 2) were crystallized from Me2SO solutions affording crystalline adducts (1–2)·Me2SO, which were characterized by X-ray crystallography at various temperatures (>40 K). The two adducts are isomorphic and exhibit in their XRD structures the heteroleptic dipole–dipole four-center contacts between the S=O and C≡N functionalities. Results of DFT calculations within the “molecular” approach based on the experimental X-ray geometries of (1–2)·Me2SO followed by the topological analysis of the electron density distribution (QTAIM analysis) at the M06-2X/x2c-TZVPPall level of theory confirm the presence of sulfoxide–nitrile heteroleptic dipole–dipole interactions in the solid state (their estimated strength does not exceed 7 kcal/mol). DFT calculations for 1·Me2SO were also performed in both the periodic and “molecular” models at the DFT M06 level of theory using DZVP and pob-TZVP bases; the results of the electron density topological analysis are similar in both models.