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-μ 2-2-[(3-chloro-2-methylphenyl)amino]-benzoato- O, O-1,3-bis-2-[(3-chloro-2-methylphenyl)amino]benzoato- O-1,2,4:2,3,4-di-μ 3-oxo-tetrakis[di- n-butyltin(IV)]

Abstract

The complexes [Me 2LSnOSnLMe 2] 2 ( 1) [Bu 2LSnOSnLBu 2] 2 ( 2) and Bu 2SnL 2.H 2O ( 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 Sn 2O 2 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.