Organotin(IV) coordination by oxime analogues of amino acids and peptides

Abstract

The complexes of four oxime analogues of amino acids and peptides (containing {O,N} donor atoms) with Bu₂SnO were prepared, with ligand to metal ratios of 1 : 1 or 1 : 2, by two different methods. The FT-IR and Raman spectra clearly demonstrated that the organotin(IV) moieties react with the {O,N} atoms of the ligands. It was found that in most cases the -COO^- group is coordinated to the central metal ion in a monodentate mode. Complex formation was accompanied by a rearrangement of the hydrogen-bonding network existing in the ligands. The complexes probably have monomeric structures. Comparison of the experimental Mössbauer δ values with those calculated on the basis of the point charge model (pqs) formalism revealed that the organotin(IV) moiety has octahedral (oct) geometry, and in certain cases trigonal-bipyramidal (tbp) geometry too.