Synthesis and spectroscopic studies of diorganotin derivatives with tolfenamic acid. Crystal and molecular structure of the first complex of tolfenamic acid, 1,2:3,4-di-μ2-2-[(3-chloro-2-methylphenyl)amino]-benzoato-O,O-1,3-bis-2-[(3-chloro-2-methylphenyl

The complexes [Me2LSnOSnLMe2]2 (1) [Bu2LSnOSnLBu2]2 (2) and Bu2SnL2.H2O (3), where HL is 2-[bis(3-chloro-2-methylphenyl)amino]benzoic acid (tolfenamic acid), have been prepared and characterized structurally by means of 19Sn Mössbauer, vibrational and 1H- and 13C-NMR spectroscopies. The crystal structure of complex 2 has been determined by X-ray crystallography. Three distannoxane rings are present to the dimeric tetraorganodistannoxanes of planar ladder arrangement with distorted trigonal-bipyramidal geometry about the five-coordinated tin centers. The structure, which has twofold symmetry, features a central Sn2O2 unit with two additional tin atoms linked at O. Pairs of tin atoms are bridged by bidentate carboxylate ligands and the external tin atoms have their coordination geometry completed by a monodentate carboxylate ligand. The tin atom geometries are similar and are based on a trigonal bipyramidal arrangement. Significant π→π stacking, C–H–π interactions and intrarmolecular hydrogen bonds stabilize this structure. The polar imino hydrogen atom on N(1) and N(2) participate in a bifurcate intramolecular hydrogen bond. In this case complex 2 is self-assembled via C–H–π and π→π stacking interactions. Tin-119 Mössbauer, vibrational and NMR data are discussed in terms of the crystal structure and the proposed structures for 1 and 3. From the variable-temperature Mössbauer effect, the Debye temperatures for 1–3 were determined.