A novel phosphovanadate of Co(III) hexammine: Co(NH3)(6)(V1.5P0.5)O6OH

The new phosphovanadate Co(NH3)(6)(V1.5P0.5)O6OH has been synthesized by a hydrothermal method at 220 degreesC. It crystallizes in the P2(1)/c space g roup with a = 9,5206(8), b = 6.9631(6), c 17.108(1), beta = 93,028(7), and Z= 4, The structural resolution using single-crystal X-ray diffraction lead s to R (F-o) = 3.63% and R-w(F-o(2))= 10.67%. This structure consists of [C o(NH3)(6)](3+) cations and [V1.5P0.5O6OH](3-) anions assembled in a distort ed rock salt arrangement. The presence of the Co(III) hexammine complex CCo (NH3)(6)](3+) is particularly original in this structure since no complexes have been isolated up to now in phosphovanadates. The V1.5P0.5O6OH diphosp hovanadate group, with one vanadium tetrahedral site and one tetrahedral si te statistically occupied by 0.5 vanadium and 0.5 phosphorus atom, correspo nds to the random distribution of V2O6OH and VPO6OH groups as confirmed by the IR spectroscopy study. Magnetic measurements show that the Co(III) cati on adopts a low spin configuration. (C) 2001 Academic Press.