Dibutyltin(IV) formulations: Synthetic aspect, spectroscopic interpretation, and computational calculation

This research article reports a series of dibutyltin(IV) complexes, Bu2SnL(n)A (1a-1d), synthesized by the reaction of sodium salts of substituted pyrazolones (L(n)H) and aromatic carboxylic acid (AH) with dibutyltin dichloride in dried THF solvent. The newly synthesized dibutyltin(IV) complexes were characterized by FT-IR, NMR (1H, 13C, 119Sn) spectroscopy, and mass study. The coordination mode of both ligands with central tin atom was explicated with spectroscopic analysis of the complexes. The spectroscopic results revealed that the substituted pyrazolone ligand coordinates to the tin atom in a bidentate fashion via enolic oxygen and a carbonyl oxygen atom. In contrast, the aromatic carboxylic acid ligand coordinates in a monodentate manner through the carboxylic oxygen atom, resulting in a penta-coordinated environment around the central tin atom. Computational calculations using density functional theory (DFT) provide insights into the optimized molecular structures, energies, Mulliken charges and distortion in bond lengths and bond angles of the newly generated complexes. The global reactivity descriptors and the Frontier Molecular Orbitals (FMOs) were calculated to understand the structural and electronic properties of dibutyltin(IV) formulations. The theoretical study explores the proposed penta-coordinated environment around tin atoms, revealing a distortion in the geometry of the complexes.