Reaction of rhenium(VII) oxide with 1,4-dioxane. Re2O6(μ2-OH)2x3C4H8O2 - a novel oxide hydroxide with metal-(1,4-dioxane) bonds

The reaction of Re2O7 with 1,4-dioxane in the presence of small amounts of H2O yields the compound Re2O6(OH)2 . 3(1,4-dioxane). It crystallizes in the triclinic space group P-1 with a = 10.907(3), b = 12.875(4), c = 7.943(2) A; α = 108.64(2), β = 103.00(2), γ = 102.29(2)0; Z = 2. The complete X-ray structure analysis (R = 2.9%) shows the crystals to contain dimeric centrosymmetric Re2O6(OH)2-units with two bridging μ2-OH groups. The ligand spheres around Re are completed towards distorted octahedra by coordinated 1,4-dioxane molecules (one O donor per Re), the latter linking the dimeric units to endless chains. The rest of the 1,4-dioxane molecules are bonded to the OH-groups through hydrogen bridges and have no contact to Re. Mean bond distances are: Re-O(bridge) 2.065 (2.059 ... 2.070(4)) A, Re-O(1,4-dioxane) 2.478 (2.469 and 2.486(5)) A, Re-O(terminal) 1.707 (1.694...1.720(5)) A. (author)