Tetrakis(phenylethynyl)tin(IV)

The asymmetric unit of the crystal structure of the title compound, [Sn(C₈H₅)₄], consists of one fourth of a discrete tin complex and one half of another which both possess nearly ideal tetrahedral symmetry; the site symmetries of the two Sn atoms are 4 and 2. The bond angles at all acetylide C atoms are almost linear. The Sn-C distances [2.076 (6) and 2.065 (6)-2.069 (6) Å in the two complexes) are short when compared to the sum of the covalent radii of C and Sn (2.177 Å), but consistent with another tetrakis(alkynyl)tin complex. The acetylenic bond distances [1.196 (7) and 1.183 (7)-1.207 (7) Å] are consistent with a triple C[triple-bond]C bond. Therefore, despite the short Sn-C distances, the ligands are mainly σ-bonded to the metal. In the solid state, these complexes form a three-dimensional network via agostic C-H interactions as a phenyl proton in the ortho position interacts with the acetylenic carbon in the α position to the tin center.