Novel Polyanionic Topologies in Ag2VAsO6 and Ag6V2As2O13

Two new silver vanadate arsenates, Ag2VAsO6 and Ag6V2As2O13, have been prepared applying high oxygen pressure syntheses in stainless-steel autoclaves. Ag2VAsO6 crystallizes in space group P1̄ with unit cell parameters a = 639.1(1), b = 646.1(1), c = 706.6(1) pm, α = 116.105(3), β = 91.759(4), γ = 90.067(4)◦, and Z = 2 (R1 = 0.058, 3935 independent reflections). The structure consists of AsO4 tetrahedra and VO6 octahedra which are linked to form two-dimensional 2 ∞[VAsO6] 2− polyanions, separated by silver cations. Ag6V2As2O13 (C2/c, a = 1895.9(2), b = 536.40(6), c = 1308.5(2) pm, β = 113.578(2)◦, Z = 4; R1 = 0.030, 2571 independent reflections) displays as primary building units AsO4 tetrahedra and VO5 trigonal bipyramids which are condensed by sharing edges to one-dimensional ∞[V2As2O13] 6− ladder-like strands, set apart by the silver cations. These heteropolyanions are without precedent.