A multinuclear NMR spectroscopy characterization of dinuclear tungsten(VI) complexes of tridentate and pentadentate meso-d-glycero-d-gulo-heptitol and d-glycero-l-gulo-heptitol

The formation of W(VI) complexes of two C-6 epimeric heptitols, namely meso-d-glycero-d-gulo-heptitol and d-glycero-l-gulo-heptitol, has been studied in aqueous solution. In alkaline medium, both heptitols form two types of dinuclear complexes which have been structurally characterized from multinuclear NMR data. In the first type T, the site of chelation is a tridentate xylo system. In the second type P, the site of chelation is a pentadentate system with a central xylo triol group. The influence of the nature and orientation of the substituents attached to the lateral carbon atoms of the chelating site upon the complex stability is discussed.