Hydrothermal synthesis and structures of the novel niobium phosphates [NbOF(PO4]N2C5H7) and [(Nb0.9V1.1)O-2(PO4)(2)(H2PO4)](N2C2H10)

摘要

Two new niobium phosphates were synthesized and their crystal structures determined from single-crystal X-ray data. [NbOF(PO4)](N2C5H7) (1) (monoclinic, space group P2(1)/c, a = 11.442(1), b = 9.1983(7), c = 9.1696(8) Angstrom, beta= 109.94(1)degrees) has a layered structure and is the first example of a negatively charged NbOF(PO4) layer analogous to the MO(H2O)PO4 (M = V, Nb) layers. The layer charge is compensated by interlayer 4-aminopyridnium cations that adopt an unusual arrangement as a consequence of H-bonding and pi-pi interactions. The interlayer aminopyridnium cations can be exchanged with alkylammonium ions which form bilayers inclined at similar to65degrees to the NbOF(PO4) layer. [(Nb0.9V1.1)O-2(PO4)(2)(H2PO4)] (N2C2H10) (2) (orthorhombic, space group Pbca, a = 15.821(2), b = 9.0295(9), c = 18.301(2) Angstrom) has a disordered three-dimensional structure based on NbO(PO4) layers cross-linked by phosphate tetrahedra, and has a similar structure to the known vanadium analog [V2O2(PO4)(2)(H2PO4)] (N2C2H10). (C) 2003 Elsevier Inc. All rights reserved. [References: 28]