A Hydrothermal Investigation of the 1/2V2O5−H2C2O4/H3PO4/NH4OH System: Synthesis and Structures of (NH4)VOPO4·1.5H2O, (NH4)0.5VOPO4·1.5H2O, (NH4)2[VO(H2O)3]2[VO(H2O)][VO(PO4)2]2·3H2O, and (NH4)2[VO(HPO4)]2(C2O4)·5H2O

Publisher Website
Google Scholar
Abstract
The 1/2V2O5−H2C2O4/H3PO4/NH4OH system was investigated using hydrothermal techniques. Four new phases, (NH4)VOPO4·1.5H2O (1), (NH4)0.5VOPO4·1.5H2O (2), (NH4)2[VO(H2O)3]2[VO(H2O)][VO(PO4)2]2·3H2O (3), and (NH4)2[VO(HPO4)]2(C2O4)·H2O (4), have been prepared and structurally characterized. Compounds 1 and 2 have layered structures closely related to VOPO4·2H2O and A0.5VOPO4·yH2O (A = mono- or divalent metals), whereas 3 has a 3D open-framework structure. Compound 4 has a layered structure and contains both oxalate and phosphate anions coordinated to vanadium cations. Crystal data: (NH4)VOPO4·1.5H2O, tetragonal (I), space group I4/mmm (No. 139), a = 6.3160(5) Å, c = 13.540(2) Å, Z = 4; (NH4)0.5VOPO4·1.5H2O, monoclinic, space group P21/m (No. 11), a = 6.9669(6) Å, b = 17.663(2) Å, c = 8.9304(8) Å, β = 105.347(1)°, Z = 8; (NH4)2[VO(H2O)3]2[VO(H2O)][VO(PO4)2]2·3H2O, triclinic, space group P1̄ (No. 2), a = 10.2523(9) Å, b = 12.263(1) Å, c = 12.362(1) Å, α = 69.041(2)°, β = 65.653(2)°, γ = 87.789(2)°, Z = 2; (NH4)2[VO(HPO4)]2(C2O4)·5H2O, monoclinic (C), space group C2/m (No. 12), a = 17.735(2) Å, b = 6.4180(6) Å, c = 22.839(2) Å, β = 102.017(2)°, Z = 6.