Structure of (VO)2P2O7

The crystal structure of the vanadium (IV) pyrophosphate that shows the remarkable ability to selectively catalyze the oxidation of butane to maleic anhydride has been accurately determined for the first time. This was facilitated by the growth of high quality (VO)2P2O7 crystals under controlled oxygen fugacity. Single crystal X-ray diffraction indicated monoclinic symmetry rather than the orthorhombic symmetry assumed in earlier studies. The space group is P21 with a = 7.28 Å, b = 16.588 Å, c = 9.58 Å, β = 89.975 Å, and Z = 4. A final R of 3.1% was obtained. Typical vanadyl environments are found for all eight crystallographically distinct vanadium atoms, and normal bond angles and distances are found for the P2O7 groups.