Intramolecular Chalcogen−Tin Interactions in (<i>o</i>-MeE-C₆H₄)CH₂SnPh₃_-<i>_n</i>Cl<i>_n</i> (E = S, O; <i>n</i> = 0, 1, 2), Characterized by X-ray Diffraction and ¹¹⁹Sn Solution and Solid-State NMR

Organotin(IV) compounds of the type (o-MeE-C6H4)CH2SnPh3-nCln were synthesized, E = O, n = 0 (1), n = 1 (2), n = 2 (3) and E = S, n = 0 (4), n = 1 (5), n = 2 (6). The complexes exhibit significant trigonal bipyramidal pentacoordination at tin as a consequence of intramolecular Sn−O (1−3) and Sn−S (4−6) interactions upon substitution of the phenyl groups by chloro groups. The intramolecular Sn−O distances in 1, 2, and 3 are 83%, 75%, and 79% of the sum of the van der Waals radii. The equivalent Sn−S values for 4, 5, and 6 are 90%, 73%, and 71%, respectively. The geometry of compound 3 is complicated by intermolecular dimerization via bridging chlorines creating a distorted octahedral geometry at tin. The related dichloro sulfur compound 6 also exhibits an intermolecular association in the form of Sn−Cl−H hydrogen bonding leading to a polymeric structure in the solid state. CPMAS 119Sn NMR spectroscopy suggests that the intramolecular Sn−E interactions persist in solution and also facilitated the discovery of a new crystalline form of 4, 4‘, that contains a Sn−S distance which is 95% the sum of the van der Waals radii.