Yttrium‐Containing Sandwich‐, Ring‐, and Cage‐Type Polyoxovanadates: Synthesis and Characterization

By the reaction of Y(NO3)3 and {Et4N}[VO3] in organic media, yttrium‐containing polyoxovanadates are synthesized and classified into sandwich‐type {Et4N}5[Y(H2O)n(V4O12)2] (1, n = 0–2), ring‐type {Et4N}6[Y(V9O27)] (2), and cage‐type {Et4N}8[Y4(OH)4V20O58] (3). Both compounds 1 and 2 contain a mononuclear yttrium cation. A yttrium cation in 1 is sandwiched by two [V4O12]4–, while that in 2 is surrounded by a single [V9O27]9– ring. In acetonitrile, both species 1 and 2 are formed simultaneously. The dominant species in solution are controlled by the presence of additives. The addition of an excess amount of pyridine drives the formation of 1, while in the presence of water or {Et4N}[VO3], the formation of 2 is preferable. Compound 3 possesses a cubane‐type tetranuclear yttrium core, [Y4(OH)4]8+, wrapped by a polyoxovanadate framework. The spherical polyoxovanadate framework of 3 exhibits new types of inorganic coordination ligands and can include a cubane unit in the framework. The vanadate framework of 3 consists of condensed [V11O33]11– rings sharing three‐coordinate VO4 units as a bridgehead, as in an adamantane framework. Sandwich‐, ring‐, and cage‐type yttrium‐containing polyoxovanadates with quite different arrangements are synthesized, and their structures are manipulated stoichiometrically by using additives.