Zur Reaktion des Rhenium(VII)-oxids mit 1,4-Dioxan – Kristallstruktur von Re2O7(OH2)2 · 2(1,4-Dioxan)

Reaction of Rhenium(VII) Oxide with 1,4-Dioxane – Crystal Structure of Re₂O₇(OH₂)₂ · 2(1,4-Dioxane) By solvolysis of polymeric Re₂O₇ with 1,4-dioxane in the presence of small amounts of H₂O two products of compositions Re₂O₆(OH)₂ · 3(1,4-dioxane) ( 1 ) and Re₂O₇ · 2H₂O · 2(1,4-dioxane) ( 2 ) are formed. From a complete X-ray single-crystal structure analysis 2 could now be characterized structurally (monoclinic, space group P2₁/c, a = 6.828(3) Å, b = 9.530(2) Å, c = 26.421(8) Å, β = 91.71(3)°, Z = 4). The compound is important as a convenient precursor for the preparation of pure rhenium trioxide. It is to be formulated as Re₂O₇(OH₂)₂ · 2(1,4-dioxane) and contains, contrary to 1 , no 1,4-dioxane coordinated to Re. The crystalline phase consists of a supramolecular arrangement of Re₂O₇(OH₂)₂ units as in “solid perrhenic acid” and of 1,4-dioxane molecules associated through O? H …? O hydrogen bridges. Analogous to dirhenium heptoxide and to solid perrhenic acid one of the rhenium atoms is in tetrahedral, the other is in distorted octahedral coordination.