6533b7d7fe1ef96bd1268cea

RESEARCH PRODUCT

Synthesis and spectroscopic characterization of R3SnIV derivatives ofN-acetyldipeptides

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description

Triorganotin(IV) derivatives of N-acetyldipeptides R3SnAcDip; RMe, Et, n-Bu, n-Oct, Cy or Ph (HAcDipN-acetylglycylglycine and N-acetylglycylvaline; RMe, n-Bu, Cy, HAcDipN-acetylglycylalanine) were obtained by neutralization of R3SnOH and HAcDip. The complexes were studied by means of 119Sn Mossbauer, IR and 1H, 13C and 119Sn NMR spectroscopy. The CSnC bond angles have been inferred by rationalization of Mossbauer nuclear quadrupole splittings as well as from NMR coupling constants. Correlations of Mossbauer isomer shifts with partial atomic charges on tin atoms have been determined: Polymeric trigonal bipyramidal structures, with near-planar R3Sn units and axial carboxylate (unidentate) and CO amide donor groups are inferred for all the compounds in the solid state, except for Cy3SnAcGlyVal for which a tetrahedral structure is proposed. In solution the complexes are monomeric; in methanol a solvent molecule is coordinated to tin which then is still in a trigonal bipyramidal environment.