Synthesis, Spectroscopic Studies, and Crystal Structures of Phenylorganotin Derivatives with [Bis(2,6-dimethylphenyl)amino]benzoic Acid: Novel Antituberculosis Agents

The novel triphenyl adduct of 2-[(2,6-dimethylphenyl)amino]benzoic acid (HDMPA; 1), i.e., [SnPh3(DMPA)] (2), the dimeric tetraorganostannoxane [Ph2(DMPA)SnOSn(DMPA)Ph2]2 (3), and the monomeric adduct [SnPh2(DMPA)2] (4), where DMPA is monodeprotonated HDMPA, have been prepared and structurally characterized by means of IR, 1H-NMR, and 13C-NMR spectroscopy. The structures of 1 and 2 have been determined by X-ray crystallography. Single-crystal X-ray-diffraction analysis of 1 revealed that there are two molecules in the asymmetric unit, HD1 and HD2, differing in conformation, both forming centrosymmetric dimers linked by H-bonds between the carboxylic O-atoms. X-Ray analysis of 2 revealed a pentacoordinate structure containing Ph3Sn coordinated to the carboxylato group. Significant CH/π interactions and intramolecular H-bonds stabilize the structures of 1 and 2, which self-assembled via CH/π and π/π-stacking interactions. The Ph3Sn adduct 2 was found to be a promising antimycobacterial lead compound, displaying activity against Mycobacterium tuberculosis H37Rv. The cytotoxiciy in the Vero cell line is also reported.