Coordination properties of adenosine-5′-monophosphate and related ligands towards Me2Sn(IV)2+ in aqueous solution

The coordination of Me2Sn(IV)(2+) to adenosine-5'-monophosphate (AMP) and the related compounds (D)-ribose-5-phosphate (R5P), (D)-glucose-1-phosphate (G1P) and (D)-glucose-6-phosphate (G6P) in aqueous solution was investigated by means of potentiometric titration, and H-1-, P-31-NMR and Mossbauer spectroscopic methods in the pH range 2-11 (I=0.1 M NaClO4, 298 K). The complex of AMP and Me2Sn(IV)(2+) precipitated at low pH was characterised by elemental analysis, FT-IR and Mossbauer spectroscopic methods. From a comparison of the pK values obtained in the presence and absence of metal ion and the stability constants for the different systems, the coordination of {N} is excluded, while bidentate coordination of the phosphate group is presumed. Mossbauer spectroscopic measurements recorded in the glassy state confirmed bidentate coordination of the phosphate and the formation of mixed hydroxo complexes in the weakly acidic, neutral and strongly basic pH range. With increasing pH, the phosphate groups were replaced by the deprotonated alcoholic {O} atoms of the sugar moiety. The solid complex proved to be tbp structure with bidentate phosphate coordination. (C) 2002 Elsevier Science Inc. All rights reserved.