Structural Characterizations of Spherical Octadecavanadates Encapsulating Na+, K+ or I- and Ellipsoidal Octadecamolybdate Encapsulating two Anions of SO42-

Polyoxoanions of tungsten, molybdenum, and vanadium have been the subject of interest since their wide variety of compositions, structures, and properties give rise to numerous important applications^1]. From the NH₄VO₃/Na₂S_x (or (NH₄)₂S_x) reaction system we synthesized several spherical octadecavanadates with Na⁺,K⁺, NH₄⁺ or I encapsulated using hydrothermal method. These complexes include (NH₄)₁₁V₁₈O₄₂(Na)]·(H₂O)₂₀ 1; (NH₄)₁₁V₁₈O₄₂(K)]·(H₂O)₆, 2; (NH₄)₁₀(Na)V₁₈O₄₂(Na)]·(H₂O)₂₆, 3; (NH₄)₁₁V₁₈O₄₂(NH4]·(H₂O)₂₀, 4; and (NH₄)₂₀(I)₇V₁₈O₄₂(I)]·(H₂O)₁₂, 5, in which the structures of 1, 2, 3, and 5 have been determined by X-ray analyses. In the analogous reaction system of (NH₄)₂MoS₄/(NH₄)₂S_x, we also obtained one ellipsoidal octadecamolybdate, (NH₄)₄Mo₁₈O₅₄(2SO₄)]·(H₂O)₄, 6 with a standard Wells-Dawson structure^2]. The Ortep drawings of the two kinds of structures are viewed as follows.