Mo^V-Mo^VI cationic ordering in the layered molybdate (C₂H₁₀N₂)[Mo₄O₁₂]

The mixed valence Mo^V-Mo^VI layered tetramolybdate (C₂H₁₀N₂)[Mo₄O₁₂] has been hydrothermally synthesized (180°C, 3 weeks, autogenous pressure). It crystallizes in the monoclinic system (space group C2) with a = 11.4090(2), b = 11.8227(2), c = 10.2305(1) Å, β = 117.549(1)° and Z = 4 at 20°C. The structure was solved from single crystal X-ray diffraction data. Full matrix anisotropic least-squares techniques led to a conventional R₁(F_o) factor of 0.044 [WR₂(F_o²) = 0.107] for 2885 reflections [I > 2σ(I)]. Its structure consists of [Mo₄O₁₂]^2- layers perpendicular to the c* axis, made up of an ordered organization of isolated tetrameric Mo^V clusters linked by edges to tetrameric Mo^VI ones. Ethylenediamine cations are located between the inorganic layers and ensure the connectivity of the structure via hydrogen bonds.