Butyltin(IV) citrates and tartrates: Structural characterization and their interaction with nucleotides

Butyltin complexes with biologically important hydroxyacids, citric HOOCCH2C(OH)(COOH)CH2COOH (C6H8O7) acid and (2R,3R)-(+)-tartaric HOOCCH(OH)CH(OH)COOH (C4H6O6) acid: [Sn(C4H9)2(C6H6O7)] (1), [Sn(C4H9)3(C6H7O7)] (2), (phenH)2[Sn(C4H9)3(C6H5O7)] (3), [Sn(C4H9)2(C4H4O6)] (4), [Sn(C4H9)3(C4H5O6)] (5), (phenH)[Sn(C4H9)3(C4H4O6)] (6) and [{Sn(C4H9)3}2(C4H4O6)] (7) have been synthesized and characterized by ESI–MS, IR and 1H, 13C and 119Sn NMR spectra. Their structures and properties in solid state and solutions were proposed on the basis of the spectroscopic data and density functional theory (DFT) calculations at B3LYP/3-21G** level. Complexes in solutions in polar solvents are five-coordinate as evidenced by 13C and 119Sn NMR spectra. Geometries of the five-coordinate complexes were optimized with B3LYP/3-21G** calculations. The 13C, 31P and 119Sn NMR spectra prove that complexes effectively interact with AMP, ATP and DAMP nucleotides forming Sn–OP bonds and N⋯H–O (nucleotide–carboxylate ligand) hydrogen bonds. In the case of dibutyltin complexes (1 and 4) nucleotides may also be coordinated as a chelating ligands via phosphate group and N7 atom of adenine residue.