Organotin(IV) triazolates: Synthesis and their spectral characterization

Some organotin(IV) triazolates of general formula RnSn(L)4 − n (where R = Me, n-Bu and Ph for n = 2; R = Me, n-Pr and n-Bu for n = 3 and HL = 3-amino-5-mercapto-1,2,4-triazole) have been synthesized by the reaction of R2SnCl2/R3SnCl with NaL in 1:2/1:1 molar ratio. Whereas, Oct2SnL2 has been synthesized azeotropically by the reaction of Oct2SnO and HL in 1:2 molar ratio. As good single crystals were not obtained, a large number of experimental techniques, viz. UV/Vis, IR, far-IR, multinuclear (1H, 13C and 119Sn) NMR and 119Sn Mössbauer spectroscopic studies, were used to accomplish a definitive characterization and determination of their most probable structures. In these compounds triazole acts as a monoanionic bidentate ligand, coordinating through Sexo and N(4). The IR and 119Sn Mössbauer spectroscopic studies allow us to deduce a highly distorted cis-trigonal-bipyramidal structure for R3SnL and a distorted skew trapezoidal-bipyramidal structure for R2SnL2, in the solid state. However, 1H, 13C and 119Sn NMR spectral studies revealed that weak bonding between tin and N(4) is further weakened in the solution leading to pseudo-tetrahedral/tetrahedral structure.