The first observation of γ-octamolybdate: Synthesis, crystal and molecular structure of [Me3N(CH2)6NMe3]2[Mo 8O26]·2H2O
The compound [Me3N(CH2)6NMe3]2[Mo 8O26]·2H2O crystallizes from an aqueous solution of sodium molybdate and [Me3N(CH2)6NMe3]Cl2, slightly acidified with hydrochloric acid. The crystals are monoclinic, space group P21/n with a = 12.42(1), b = 12.897(3), c = 15.74(1) Å, β = 106.41(5)° and Z = 2. The structure was determined by direct methods and refined by least squares to R = 0.030 for 3153 observed reflections and 315 parameters. The [Mo8O26]4- anion is composed of six MoO6 octahedra interlinked along edges and two MoO5 trigonal bipyramids each sharing two edges with the octahedra. This is different from the previously observed α and β isomers of [Mo8O26]4- and lends credence to one of the proposed mechanisms for their interconversion.