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Synthesis and spectroscopic characterization of diethyltin (IV) derivatives of dipeptides: Crystal and molecular structure of diethyltin glycyltrosinate
Author(s) -
Vornefeld Michael,
Huber Friedo,
Preut Hans,
Ruisi Giuseppe,
Barbieri Renato
Publication year - 1992
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.590060110
Subject(s) - chemistry , glycylglycine , crystallography , trigonal bipyramidal molecular geometry , crystal structure , denticity , tin , monomer , stereochemistry , dipeptide , molecular geometry , molecule , peptide , amino acid , glycine , organic chemistry , biochemistry , polymer
Dipeptide complexes of the diethyltin(IV) moiety, Et 2 SnL, have been synthesized, H 2 L being glycylglycine (H 2 GlyGly), glycylalanine (H 2 GlyAla), alanylalanine (H 2 AlaAla), glycylvaline (H 2 GlyVal), valylvaline (H 2 ValVal), glycylmethionine (H 2 GlyMet), glycyltyrosine (H 2 GlyTyr). The crystal and molecular structure of the complex Et 2 SnGlyTyr has been determined by singlecrystal X‐ray diffraction. It consists of monomeric units, with the tin atom having a considerably distorted trigonal bipyramidal environment. The dipeptide acts as a tridentate ligand bonding the tin of the C 2 Sn fragment (equatorial carbon atoms) with the peptide nitrogen atom (equatorial) and axial (monodentate) carboxyl oxygen and amino nitrogen atoms, into a monomeric unit. Bond lengths and angles are reported. Infrared spectroscopic data show the occurrence of monodentate carboxyl in all solid compounds, as well as in methanol solutions of some representative complexes. 119 Sn Mössbauer spectroscopic data, and their rationalization through point‐charge model (literal version) calculations of the parameter nuclear quadrupole splitting (ΔE) confirm the general occurrence of trigonal bipyramidal structures of the Et 2 SnGlyTyr type, in the solid state, and give evidence of variations of the CSnC angle in the individual Et 2 SnL species. Monomers occur in CH 3 OH solution as suggested by osmometric measurements. 13 C and 119 Sn NMR spectroscopic data in CD 3 OD show the persistence of the solid‐state structures also in the solution phase, where the order of magnitude of the CSnC angles, as estimated from the coupling constants | 1 J ( 119 Sn, 13 C)|, corresponds to that shown by Et 2 SnGlyTyr in the solid state. 119 Sn Mössbauer parameters of Et 2 SnGlyGly in frozen CH 3 OH solution are consistent with the assumptions from the NMR studies.