TOTAL SYNTHESIS OF DECAVANADATES OF ORGANIC-BASES - X-RAY CRYSTAL-STRUCTURES OF 4 DECAVANADATES

Decavanadate solutions react with pyridine, 3-methylpyridine, 4-methylpyridine and 2-ethylpyridine to form orange-yellow or orange-red compounds: tetrakis(pyridinium)dihydrogen decavanadate [(C5H5NH)4(V10O28H2)] (A1); tetrakis(4-methylpyridinium)dihydrogen decavanadate dihydrate [(C6H7NH)4(V10O28H2)2H2O] (A2); tetrakis(2-ethylpyridinium)dihydrogen decavanadate [(C7H9NH)4(V10O28H2)] (A3); tetrakis(3-ethylpyridinium)dihydrogen decavanadate [(C7H9NH)4(V10O28H2)] (A4); hexakis(pyridinium)decavanadate [(C5H5NH)6(V10O28)] (B1); hexakis(3-methylpyridinium)decavanadate [(C6H7NH)6(V10O28)] (B2); and the hexakis(4-methylpyridinium)decavanadate [(C6H7NH)6(V10O28)] (B3). These compounds were characterized by elemental analysis, IR spectroscopy and thermogravimetric methods in the solid state and UV spectroscopy in solution. The X-ray crystal structures of A1, A2, A4 and B3 are also reported. Structural results confirm, in the solid state, the basicity sequence given by other authors, that could be related to the different capacity of charge redistribution of the distinct types of oxygen atoms on the surface of the polyanion.