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Crystal Structure and Raman Spectroscopy of FeVMoO 7 and CrVMoO 7 with MoO Double Bonds

1998; American Chemical Society; Volume: 37; Issue: 13 Linguagem: Inglês

10.1021/ic980100u

1520-510X

Xiandong Wang, Kevin R. Heier, Charlotte L. Stern, Kenneth R. Poeppelmeier,

Catalytic Processes in Materials Science

Single crystals of FeVMoO7 and CrVMoO7 were grown by a flux method from Fe2O3−V2O5−MoO3 and Cr2O3−V2O5−MoO3 melts, respectively. Single-crystal X-ray diffraction revealed that FeVMoO7 and CrVMoO7 are isostructural, in which V5+ and Mo6+ ions in the [VMoO7]3- units are crystallographically distinct, and one type of oxygen is bonded only to molybdenum, forming a MoO double bond. These rare structural features were also studied by infrared and Raman spectroscopy. Raman MoO stretching frequencies are consistent with the assignments made in previous surface studies of molybdate catalysts. Crystal data for FeVMoO7: triclinic, space group P1̄ (No. 2), with a = 5.564(1) Å, b = 6.669(1) Å, c = 7.909(1) Å, α = 97.65(1)°, β = 90.33(1)°, γ = 101.32(2)° and Z = 2. Crystal data for CrVMoO7: triclinic, space group P1̄ (No. 2), with a = 5.5273(9) Å, b = 6.582(1) Å, c = 7.8650(9) Å, α = 96.19(1)°, β = 89.87(1)°, γ = 102.01(1)°, and Z = 2.