Ionothermal synthesis and characterization of alkali metal polyoxometallates: Structural trends in the (emim)m[An(Mo8O26)] (emim = 1-ethyl-3-methylimidazolium; m = 2,3; n = 1,2; A = K, Rb, Cs) group of compounds

Three novel octamolybdates (emim)3K(Mo8O26) (1), (emim)3Rb(Mo8O26) (2) and (emim)2Cs2(Mo8O26) (3) (emim = 1-ethyl-3-methylimidazolium) have been prepared by ionothermal reactions using (emim)Br as a solvent. The structures contain octamolybdate anions [β-Mo8O26]4–. In compounds 1 and 2, [β-Mo8O26]4– units are linked by alkali metal cations to form 1D chain structures, while Cs cations in the compound 3 link to polyoxoanions to form a 2D layered structure.