COMPOUNDS OF L(+)-ASCORBIC ACID WITH METALS .8. TITANIUM(IV) COMPLEXES OF L(+)-ASCORBIC ACID AND 5,6-O-ISOPROPYLIDENE-L-ASCORBIC ACID

The reactions of titanium(IV) halogen compounds with the monoalkali and dialkali metal salts of L(+)-ascorbic acid and 5,6-O-isopropylidene-L-ascorbic acid, respectively, in EtOH or THF as solvent, generally result in the formation of complexes of the appropriate dianions. Whereas the ascorbate dianion exclusively forms an ate-complex, this is not observed in the case of the 5,6,O-isopropylidene-L-ascorbate dianion. The results of our spectroscopic studies show the ene-diolate group to be the coordination site for both of the dianions. However, for the 5,6-O-isopropylidene-L-ascorbate dianion an additional weak interaction between one of the O atoms of its dioxolane ring and Ti(IV) cannot be excluded. © 1990.