Studies of rhenium–carboxylate complexes. III. The crystal and molecular structure of tetra-μ-n-butyratodirhenium(III) diperrhenate

Abstract

One of the compounds obtained by the reaction of rhenium(III) chloride with n-butyric acid while exposed to oxygen has been shown by single crystal X-ray diffraction to be tetra-μ-n-butyratodi-rhenium(III) diperrhenate. The crystals are triclinic with lattice parameters a = 7.836(8) Å, b = 10.746(8) Å, c = 8.773(8) Å, α = 88.9(1)°, β = 106.5(1)°, and γ = 98.0(1)°. The space group is [Formula: see text] and there is one formula unit per cell. A total of 1593 independent reflections were examined and the structure was refined by full 3-dimensional least-squares to an R value of 0.123. Two rhenium environments are found, one consisting of a dimer unit bridged by 4 carboxylate groups and the other a per-rhenate group. This latter group, showing a mean Re—O distance of 1.75 Å, shares an oxygen atom with a rhenium atom in the dimer unit, and this Re—O bond length is 2.18 Å long. The structure results from packing of short chains, consisting of the dimer unit and the 2 perrhenate groups, running roughly parallel to the [111] direction.