| Abstract: | A new layered phosphate, Na7Y2(P2O7) 2(P3O10), containing both [P2O7]4? and [P3O10]5? groups, has been prepared. It crystallizes in the monoclinic space group P2/c with a = 16.205(4), b = 5.3746(9), c = 12.309(4) Å, β = 97.96(2)°, V = 1061.7(5) Å3 and Z = 2. The structure was solved and refined to R1 = 0.0298 and wR2 = 0.0698 for 1844 independent reflections with I > 2σ(I). It consists of layers of corner and edge-sharing YO7 polyhedra, P2O7 and P3O10 groups. Each layer is built up from two parallel [YP2O7] slabs, held together by the P3O10 groups. This arrangement gives rise to intersecting tunnels within the layer. The Na+ cations are located in the tunnels and between the layers. Both P2O7 and P3O10 groups contain unshared oxygen atoms directed toward the interlayer space and toward the tunnels. The P2O7 groups show a staggered configuration. In addition to this original layered framework, the title compound provides the third example of a compound containing a mixed anion of [P2O7]4? and [P3O10]5?. The structure was compared with the two previously reported ones, containing such a mixed anion: NH4Cd6(P2O7) 2(P3O10) [6] and Cs2Mo5O2(P2O7)3 · (P3O10) [7]. |
