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Abstract:
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 P (1) over bar with unit cell parameters a = 639.1(1), b = 646.1(1), c =706.6(1) pm, a = 116.105(3), beta = 91.759(4), gamma = 90.067(4), and Z = 2 (R-1 = 0.058, 3935 independent reflections). The structure consists of AsO4 tetrahedra and VO6 octahedra which are linked to form two-dimensional (2)(infinity)[VAsO6](2-) polyanions, separated by silver cations. Ag6V2As2O13 (C2/c, a = 1895.9(2), b = 536.40(6), c = 1308.5(2) pm, beta = 113.578(2)degrees, Z = 4; R-1 = 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 (1)(infinity)[V2As2O13](6-) ladder-like strands, set apart by the silver cations. These heteropolyanions are without precedent.
