Monosaccharides as silicon chelators: pentacoordinate bis(diolato)(phenyl)silicates with the cis-furanose isomers of common pentoses and hexoses.
Five-coordinate phenylsilicates are formed from the reaction of trimethoxy(phenyl)silane with monosaccharides in methanol in the presence of a stoichiometric amount of base. Five complexes have been isolated and characterized with two ketoses and three aldopentoses. The silicon central atom in [K([18]crown-6)][PhSi(beta-D-Fruf 2,3H-2)2].MeOH (1, Fru=fructose) is part of two chelate rings, with the ligands being beta-D-fructofuranose-O2,O3 dianions. The beta-furanose isomer is best suited for silicon ligation because it exhibits a torsion angle close to 0 degrees for the most acidic diol function, thus assuring a flat chelate ring. The same structural principles are also found in [K([18]crown-6)][PhSi(beta-D-Araf1,2H-2)2].2 MeOH (2, Ara=arabinose), [K([18]crown-6)][PhSi(alpha-D-Ribf1,2H-2)2] (3, Rib=ribose), [K([18]crown-6)][PhSi(alpha-D-Xylf1,2H-2)2]. acetone (4, Xyl=xylose), and [K([18]crown-6)][PhSi(alpha-D-Rulf2,3H-2)2] (5, Rul=ribulose).
Klüfers
Peter
P
Department Chemie der Ludwig-Maximilians-Universität, Butenandtstrasse 5-13 (Haus D), 81377 München, Germany. kluef@cup.uni-muenchen.de
Kopp
Florian
F
Vogt
Martin
M
D002614:Chelating Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005663:Furans / Q000737:chemistry*; D006601:Hexoses / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009005:Monosaccharides / Q000737:chemistry*; D010429:Pentoses / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry; D013237:Stereoisomerism
D002614:Chelating Agents; D005663:Furans; D006601:Hexoses; D009005:Monosaccharides; D010429:Pentoses; D017640:Silicates; D012825:Silicon