Crystal and molecular structure of tetra-acetyl diborate

Abstract

The crystal structure of the title compound has been solved by direct methods from three-dimensional X-ray diffractometer data and refined by least-squares methods to R 0·050 for 1337 independent reflections. All the hydrogen atoms have been located. The crystals are monoclinic, space group P2₁/c, with a= 7·528, b= 8·231, c= 19·891 Å, β= 96·0°, Z= 4. Two distorted tetrahedra sharing a vertex are present in the molecule; two acetoxy-groups have only a B–O bond, whereas the remaining two are each linked to both boron atoms. The abnormally long and short B–O bond lengths (range 1·384—1·561 Å) are interpreted in terms of detailed valence neutralization. The molecules do not present strong intermolecular contacts, as shown by the considerable instability of the compound and the great thermal motion of the atoms.