VO(ReO4)2:: solid state and structural chemistry

VO(ReO4)(2) was prepared by an oxide-reduction reaction between V2O5 and ReO3 oxides at 700 degrees C. It appears as green micro-crystalline powder and single crystals. It crystallizes in the orthorhombic system, space group Cmc2(1), with cell parameters a = 5.7110(4), b = 14.699(1), c = 8.8230(4) Angstrom and four formula units in the cell. The structure investigation provided the formula supported by a low R value of 0.038 from 1094 independent hkl reflections. The presence of V + IV is confirmed by magnetic measurement, but clearly enlightened by the structural features with the presence of a VO2+ vanadyl group. Re(VII) occupy two independent tetrahedra sharing corners with the VO5 square pyramid forming infinite [VO(ReO4)(2)](n) ribbons along the [100] direction. These ribbons are linked together by a sixth longer V-O interaction (2.29 Angstrom), thus building a distorted VO6 octahedron and defining layers parallel to (021) plane. The layers are held together by a Van der Waals interaction. VO(ReO4)(2) is obviously the right formula of the early reported phase 'V2Re2O11', the chemistry and structural determination being revisited. (C) 2000 Editions scientifiques et medicales Elsevier SAS. All rights reserved.