Organotin‐Drug Interactions. Organotin Adducts of Tenoxicam: Synthesis and Characterization of the First Organotin Complex of Tenoxicam

The synthesis and spectral characterization of the novel organotin complexes SnBu₂(ten)] ( 1 ) and SnBu₂(Hten)₂] ( 2 ) of the potent and widely used anti‐inflammatory drug tenoxicam (H₂ten) are reported. A crystal‐structure determination of 1 showed that, in this complex, the ligand is doubly deprotonated at the hydroxy O‐atom and the amide N‐atom and is coordinated to the SnBu₂ fragment via four‐ and six‐membered chelate rings. An extended network of Sn−O−Sn, C−H⋅⋅⋅O and C−H⋅⋅⋅π contacts lead to aggregation and a supramolecular assembly. Potentiometric titrations in nonaqueous solutions support the ionization of the drug by removal of the second H‐atom, the amide H‐atom, in the presence of the diorganotin(IV) fragment. The K_a values of the poorly H₂O‐soluble drug tenoxicam were obtained spectrophotometrically in aqueous solutions of constant ionic strength.