Diorganotin(VI) complexes of N-acetylamino acids

Sixteen complexes of general formula R₂SnL₂ and R₂(L)SnOSn(L)R₂ (where L = N-acetyl-L-leucine or N-acetyl-L-phenylalanine) R = CH₃, C₂H₅, n-C₄H₉, or n-C₈H₁₇) have been prepared by interaction between the ligand and R₂SnO in 2:1 or 1:1 molar ratio. The complexes were characterized by IR, ₁H NMR and ¹¹⁹Sn Mössbauer spectroscopy. All the 2:1 complexes are assigned six-coordinate, distorted octahedral geometry with chelating carboxylate groups, while the 1:1 complexes have oxygen-bridged binuclear five-coordinate, trigonal-bipyramidal configurations. The amido ?CO and ?NH groups are hydrogen bonded in the solid state.