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Anion Selectivity of Tetravalent Tin Compounds in Membranes Studied by 119 Sn‐, 13 C‐ and 1 H‐NMR
Author(s) -
Pham HungViet,
Pretsch Ernö,
Fluri Karl,
Bezegh Andras,
Simon Wilhelm
Publication year - 1990
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19900730712
Subject(s) - chemistry , membrane , selectivity , potentiometric titration , substituent , inorganic chemistry , solvent , ion , aqueous solution , tin , dissociation (chemistry) , stability constants of complexes , organic chemistry , biochemistry , catalysis
The fundamental molecular aspects of trialkyltin compounds of the type R 3 SnY have been investigated in view of their applicability as ion‐selective components in solvent polymeric membranes. The interaction between these compounds and anions has been studied using 119 Sn‐ and 13 C‐NMR. Neutral tetracoordinated trialkyltin compounds form a negatively charged pentacoordinated complex upon interaction with Cl‐ions in homogeneous organic phases as well as in membranes in contact with aqueous solutions. Although in a homogeneous phase, the electronegative substituent Y determines the complex‐formation constant, it has no influence on the potentiometric anion selectivity in liquid membranes containing trialkyltin carriers R 3 SnY with different Y. The observed selectivity pattern is not given by the magnitude of the stability constants in a homogeneous phase but is dictated by the prevailing association‐dissociation process leading to tetracoordinated compounds which change in constitution due to varying sample composition, The results obtained from equilibrium studies of tetravalent mono tin compounds with anions in both homogeneous phase and in two‐phase systems confirm the earlier hypothesis that trialkyltin compounds incorporated in solvent polymeric membranes act as electrically neutral carriers for anions.