Studies of rhenium–carboxylate complexes. I. Tris(μ-i-butyrato)di(chlororhenium(III)) perrhenate

Abstract

One of the compounds obtained by reacting rhenium(III) chloride with isobutyric acid while exposed to oxygen has been shown by single crystal X-ray diffraction to be tris(μ-i-butyrato)di(chlororhenium(III)) perrhenate. The crystals are monoclinic with lattice parameters a = 8.980(5) Å, b = 17.790(8) Å, c = 15.361(8) Å, and β = 114.4(1)°. The space group is P21/c and there are 4 formula units per cell. A total of 1729 independent reflections were examined and the structure was refined by full three dimensional least squares to an R value of 0.114. Two Re environments are found, one consisting of a dimer unit bridged by three carboxylate groups with a chlorine atom per rhenium and the other as a perrhenate group. This latter group, showing a mean Re—O distance of 1.74 Å, shares an oxygen atom with a Re in the dimer unit, and this Re—O bond length is 2.28 Å long. The structure consists of a packing of chains of alternate dimers and perrhenate groups running parallel to the c axis.