Vanadyl oxalatophosphate compounds (C2H10N2)[VO(HPO4)]2(C2O4) and (CH6N3)2[[VO(HPO4)]2(C2O4) and their thermal transformation to (VO)2P2O7 via VOHPO4

The vanadyl oxalatophosphates (C2H10N2)[VO(HPO4)](2)(C2O4), 1, and (CH6N3)(2)[VO(HPO4)](2)(C2O4), 2, have been synthesized hydrothermally and characterized by a combination of techniques including infrared spectroscopy, single-crystal/powder X-ray diffraction, scanning/transmission electron microscopy, thermogravimetric analysis, and magnetic susceptibility measurements. The structures of 1 and 2 contain the same type of {[VO(HPO4)](2)(C2O4)}(2-) layer, including both oxalate and phosphate anions coordinated to vanadium cations, as found in the previously reported (NH4)(2)[VO(HPO4)](2)(C2O4).H2O. Above similar to 550 degreesC, 1 and 2 transform to (VO)(2)O-7, the catalyst for the oxidation of butane to maleic anhydride. An intermediate phase with the composition VOHPO4 is observed in the decomposition reactions. Crystal data: (1) triclinic, space group P (1) over bar (no. 2); a = 6.3595(7) Angstrom, b = 6.6236(7) Angstrom, c = 9.224(1) Angstrom, alpha = 98.216(2)degrees, beta = 108.128(2)degrees, gamma = 100.672(2)degrees, V = 354.42(7) Angstrom (3), Z = 1; (2) triclinic, space group P (1) over bar (no. 2); a = 6.3825(8) Angstrom, b = 7.8877(9) Angstrom, c = 9.202(1) Angstrom, alpha = 66.602(2)degrees, beta = 71.757(2)degrees, gamma = 79.821(2)degrees, V = 403.07(8) Angstrom (3), z = 1.