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

VO(ReO4)(2) was prepared by an oxide-reduction reaction between V2O5 and Re O3 oxides at 700 degrees C. It appears as green micro-crystalline powder an d 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) A ngstrom and four formula units in the cell. The structure investigation pro vided 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 measureme nt, but clearly enlightened by the structural features with the presence of a VO2+ vanadyl group. Re(VII) occupy two independent tetrahedra sharing co rners with the VO5 square pyramid forming infinite [VO(ReO4)(2)](n) ribbons along the [100] direction. These ribbons are linked together by a sixth lo nger V-O interaction (2.29 Angstrom), thus building a distorted VO6 octahed ron and defining layers parallel to (021) plane. The layers are held togeth er by a Van der Waals interaction. VO(ReO4)(2) is obviously the right formu la of the early reported phase 'V2Re2O11', the chemistry and structural det ermination being revisited. (C) 2000 Editions scientifiques et medicales El sevier SAS. All rights reserved.