ENDOR spectra of the intercalated water molecules in vanadyl(IV, V) phosphate pentahydrate

Abstract

The ENDOR spectra of the metastable expanded layer solid VOPO₄·5H₂O and its congener VOPO₄·2H₂O [both containing very small amounts of vanadium (IV)] have been measured at 4 K. The latter gave no ENDOR, whereas the former provided a spectrum in which three different proton signals ascribable to two interlayer water molecules were detected. From a reconstruction of the interlayer, taking into account the layer expansion of 3.1 Å due to the intercalated water molecules, it is suggested that VOPO₄·5H₂O is an example of a ‘pillared’ material.