Synthesis and structural insights of benzothiazole-appended 2,6-di picolinamide-based Sn(IV) complexes

Four diorganotin complexes of the compositions [Me₂Sn(L)]·0.5C₆H₅CH₃ (1), [n-Bu₂Sn(L)] (2), [Bn₂Sn(L)] (3) and [n-Oct₂Sn(L)] (4) were synthesized by reacting R₂SnO (R = Me, n-Bu, Bn or n-Oct) with N²,N⁶-bis(benzo[d]thiazol-2-yl)pyridine-2,6-dicarboxamide (H₂L, where H₂ denotes the two acidic protons) in refluxing toluene. Compounds were characterized by FT-IR (ATR mode), ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy, as well as high-resolution mass spectrometry. The solid-state structures of compounds 1–3, along with their pro-ligand H₂L, were investigated through single-crystal X-ray diffraction studies. In compounds 1–3, the dianionic tridentate pyridine dicarboxamide ligand acts as a κ-N³ tridentate chelator, coordinating to the equatorial plane, while the coordination sphere of Sn(IV) ion is completed by two axial Sn-R ligands, resulting in a distorted trigonal bipyramidal geometry.