Short and Linear Intermolecular Tetrel Bonds to Tin. Cocrystal Engineering with Triphenyltin Chloride

Group 14 (tetrel) elements potentially provide a region of low electronic density (σ-hole) and elevated electrostatic potential, which acts as an electrophilic site to form attractive interactions with electron-rich moieties. Tetrel bonds are the result of net attractive interaction between an electrophilic region associated with a tetrel atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. Here, we describe a systematic study of the potential utility of tetrel bonds to tin for engineering novel cocrystalline architectures. We report the preparation of 10 new tetrel-bonded cocrystals of triphenyltin chloride with various Lewis bases featuring oxygen and nitrogen electron donor atoms. Single-crystal X-ray diffraction studies reveal that the formation of short and directional Sn···O and Sn···N tetrel bonds along the extension of the Cl–Sn covalent bond is chiefly responsible for the self-assembly of the two complementary components. Normalized contact parameters of approximately 0.6, tetrel bond angles of approximately 170–180°, and lengthening of the covalent Sn–Cl bond by 6–9% upon cocrystallization are all characteristic of the observed tetrel bonds to tin. Substantial changes in the isotropic 119Sn chemical shifts suggest the persistence of the tin tetrel bond in solution.