Application of EXAFS and XANES Methods in Coordination Chemistry of Carbohydrates and Their Derivatives

Abstract

A summary is presented of the results obtained on metal complexes of carbohydrates (aldoses, ketoses and mono-, di- and polysaccharides) and their derivatives (aldonic and alduronic acids, polyalcohols, amino sugars, and amino acid sugar adducts). The structural parameters (coordination number, bond distance, and Debye–Waller factor) measured by extended X-ray absorption fine structure (EXAFS) spectroscopy obtained earlier on transition metals [Cu(II), Fe(III), Ni(II), Zn(II), Co(II), Ag(I), Mn in different oxidation states and organotin(IV)] complexes are discussed. In addition we report here the preparation of Bu₂Sn(IV)²⁺ complexes of rutin {3-[6-O-(6-deoxy-α-L-mannopyranosyl)-(β-D-glucopyranosyl)oxy]-2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4H-1-benzopyran-4-one} and quercetin (containing {O,O} donor atoms) in ligand to metal ratios of 1:1 and 1:2. The analytical data revealed the formation of well-defined complexes. The local structures of the complexes were determined by an EXAFS method. It was found that the Sn–O bond distances in the first coordination sphere are closed the values found in Et₂Sn(IV) complexes with nonprotected carbohydrates.