Structural comparison of iron tetrapolyvanadate Fe2V4O13 and iron polyvanadomolybdate Fe2V3.16Mo0.84O13.42: A new substitution mechanism of molybdenum(VI) for vanadium(V)

摘要

Single crystals of the iron tetrapolyvanadate Fe2V4O13 and the iron polyvanadomolybdate Fe2V3.16Mo0.84O13.42 were grown from Fe2O3/V2O5 and Fe2O3/V2O5/MoO3 melts, respectively. Single-crystal X-ray diffraction revealed that the two structures are closely related. Both contained isolated Fe2O10 octahedral dimers with similar orientations. The unusual U-shaped V4O136- clusters in Fe2V4O13 were ordered while the U-shaped [V3.16Mo0.84O13.42](6-) clusters in Fe2V3.16Mo0.84O13.42 were disordered. The substitution of molybdenum(VI) for vanadium(V) revealed a new substitution mechanism, in which a corresponding stoichiometric amount of oxygen was brought into the structure for charge balance with no reduction of the V5+ and Mo6+ ions. Crystal data: for Fe2V4O13, monoclinic, space group P2(1)/c (No. 14), with a = 8.300(2) Angstrom, b = 9.404(6) Angstrom, c = 14.560(2) Angstrom, beta = 102.08(1)degrees, and Z = 4; for Fe2V3.16Mo0.84O13.42, monoclinic, space group P2(1)/c (No. 14), with a = 7.678(1) Angstrom, b = 9.456(2) Angstrom, c = 8.336(2) Angstrom, beta = 109.50(2)degrees and Z = 2. [References: 41]