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A study of dimethyltin(IV)‐ L ‐cysteinate in aqueous solution
Author(s) -
Silvestri Arturo,
Duca Dario,
Huber Friedo
Publication year - 1988
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.590020503
Subject(s) - chemistry , deprotonation , carboxylate , aqueous solution , trigonal bipyramidal molecular geometry , tin , medicinal chemistry , mössbauer spectroscopy , chelation , molecule , stereochemistry , inorganic chemistry , nuclear magnetic resonance spectroscopy , crystallography , ion , organic chemistry
The in vivo activity of some R 2 Sn‐ L ‐cysteinate complexes (R = Me, Et, n‐Bu) against murine P‐388 leukaemia has been tested. Only the Et 2 Sn(IV) complex showed a marginal positive effect. Trigonal bipyramidal tin environments with two carbon (R) atoms and the sulfur atom in the equatorial plane and oxygen (carboxylate) and nitrogen (NH 2 ) in apical positions have been proposed for the solid compexes (R = Me, Et, n‐Bu, Ph) on the basis of experimental Mössbauer parameters and infrared (IR) data. Aqueous solutions of the Me 2 SnL‐cysteinate have been studied by IR, 1 H NMR and 119 Sn Mössbauer spectroscopy (in frozen solution) at different pH values to identify the Me 2 Sn(IV) species present. At pH > 2 the dimethyltin aquocation is complexed by the ionized sulfhydryl group of L ‐cysteine to form a five‐coordinated species. With increasing pH values, NH 3 + is deprotonated and a chelate is proposed with both the sulfhydryl and the amino group bonded to tin, one water molecule or (at still higher pH values) one hydroxyl ion occupying the fifth coordination site of a trigonal bipyramid around tin. Finally at pH > 10 the NH 2 group is substituted by a hydroxyl ion.