The single-crystal X-ray diffraction structure of the title compound, [SnCl(C6H5)3]·C18H21OP, is reported. The 1:1 cocrystal features a short and directional tetrel bond between tin and oxygen. The tin–oxygen distance is 2.346 (4) Å, representing 62% of the sum of the van der Waals radii of Sn and O. The Cl—Sn...O angle is 174.0 (1)° and this nearly linear arrangement is consistent with a tetrel bond formed via a σ-hole opposite the tin–chlorine covalent bond. Some weak C—H...Cl interactions are noted between adjacent molecules.
