PREPARATION AND CRYSTAL-STRUCTURES OF THE VANADIUMPHOSPHATES VPO4-CENTER-DOT-2H2O AND .12(PO4)(4)(OH)(3.36)(H2O)(0.64)CENTER-DOT-0.84H2O

Ten days of a hydrothermal reaction of V2O5, H3PO4, tripropylamine and H2O in a molar ratio of 1:7:10:1400 at 200 degrees C yielded a green compound VPO4 . 2H(2)O and a dark green phase V-5.12(PO4)(4)(OH)(3.36) (H2O)(0.64). 0.84H(2)O. The crystal structure of VPO4 . 2H(2)O was sol ved in space group P2(1)/n with the cell constants: a = 5.3112(2) Angs trom, b = 9.8447(2) Angstrom, c = 8.6536(2) Angstrom and beta = 91.23( 1)degrees. It was found to be isostructural with the minerals metavans cite AlPO4 . 2H(2)O and metastrengite FePO4 . 2H(2)O. The net of prima ry bonds in the metavariscite-type compounds is net number 7 of A. F. Wells (Acta Cryst, vol. 7, p. 545, 1954). The I4(1)/amd with a = 5.164 6(1) Angstrom and c = 12.9217(4) Angstrom. The compound is isostructur al with the mineral caminite MgSO4 . 0.33Mg(OH)(2) . 0.33H(2)O and sim ilar to synthethic lipscombite Fe22+Fe43+(PO4)(4)(OH)(4).