PREPARATION AND CHARACTERIZATION OF VO(HPO4) multiplied by (times) 0. 5H2O AND ITS TOPOTACTIC TRANSFORMATION TO (VO)2P2O7.

Article abstract of DOI:10.1021/ja00338a020

Vanadyl hydrogen phosphate hemihydrate, VO(HPO//4) multiplied by (times) 0. 5H//2O, has been characterized through a combination of techniques including infrared spectroscopy, paper chromatography, X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis and magnetic susceptibility measurements. It crystallizes in the orthorhombic system, a equals 7. 434 (2) A, b equals 9. 620 (2) A, c equals 5. 699 (1) A in space group Pmmn or P2//1mn. The structure consists of two-dimensional layers of HPO//4**2** minus anions and pairs of antiferromagnetically coupled V**4** plus cations. The layers are held together by strong hydrogen bonding. Above approximately 350 degree C, VO(HPO//4) multiplied by (times) 0. 5H//2O undergoes a topotactic dehydration to (VO)//2P//2O//7, an active and selective catalyst for the oxidation of butane to maleic anhydride.