Synthesis and crystal structures of a polymeric trimethyltin(IV) and a tetranuclear dibutyltin(IV) complex with azo-carboxylates derived from 4- or 3-amino benzoic acid and naphthalen-1 or 2-ol

Abstract

Complex 1 was synthesized by the reaction of 4-(4-hydroxynaphthylazo)-benzoic acid with trimethyltin(IV) chloride in anhydrous methanol using triethylamine as base while 2 was synthesized by the reaction of 3-(2-hydroxynaphthylazo)-benzoic acid with dibutyltin(IV) oxide in anhydrous toluene. The complexes were characterized by elemental analysis, IR, and multinuclear (¹H, ¹³C, and ¹¹⁹Sn) NMR spectroscopy. The coordination behavior and geometries around tin in 1 and 2 were established by X-ray crystallography while geometries of the complexes in solution were determined by ¹¹⁹Sn-NMR spectroscopy. The polymeric 1 displayed slightly distorted trigonal bipyramidal geometry around the tin with the equatorial plane occupied by three methyl groups and the axial positions occupied by a carboxylate oxygen and a phenoxide oxygen of another ligand. The tetranuclear 2 exhibited a bis[dicarboxylatotetraorganodistannoxane] type structure with a non-centrosymmetric Sn₂O₄ core where the central Sn₂O₂ ring was connected to two exo-cyclic tin ions through μ₃-oxo atoms. The coordination geometry around exo- and endo-cyclic tin ions was distorted octahedral and deformed square pyramidal, respectively. ¹¹⁹Sn NMR spectral study suggested four-coordinate tetrahedral 1 while six- and five-coordinate structures around exo- and endo-cyclic tin ions for 2 in solution.

Graphical Abstract

Keywords:

• Trimethyltin
• dibutyltin
• X-ray crystallography
• exo- and endo-cyclic
• NMR spectroscopy

Acknowledgements

We thank IISc. Bangalore, for providing NMR spectra.

Disclosure statement

No potential conflict of interest was reported by the authors.