Rb2V2O3(HAsO4)2(H2AsO4).H2O: A MIXED-VALENCE VANADIUM(IV,V) ARSENATE. Wen-Jiuan Tsai, Sue-Lein Wang*, Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043
A new mixed-valence vanadium hydrogen arsenate, Rb2V2O3 (HAsO4)2(H2AsO4).H2O has been synthesized under hydro-thermal conditions and its structure was determined from single-crystal X-ray diffraction data. Intensity measurements were performed on a CCD area detector system. Crystal data: H6As3Ol6 Rb2V2, monoclinic, P21/n, a = 9.7162(1) Å, b = 11.2839(2) Å, c = 13.8463(2) Å, [[beta]] = 100.843(1)deg., V = 1490.95(5) Å3, Z = 4, and R = 0.0445 for 2378 unique reflections. The structure is composed of Rb+ cations, water molecules and [(V4O6)(HAsO4)4 (H2AsO4)2]4- cluster anions, in which two of the edge-sharing pairs of VO6 octahedra are connected by four HAsO4 and two H2AsO4 groups. Variable-temperature powder magnetic susceptibility data confirm the presence of one V4+ and one V5+ ion per formula unit. In this presentation, the hydrothermal synthesis, single-crystal structure, thermal analysis, and magnetic study of Rb2V2O3(HAsO4)2(H2AsO4).H2O will be given. Structural relationship to A2Mo2O5(HAsO4)2.H2O (A = Cs and C5H5NH) is also discussed.