X-ray Crystal Structure Investigation of Re(hfac)₃, Re(acac)₃, and Re(acac)₃ReO₄.

Abstract

Re(hfac)₃ has been found to crystallize in a hexagonal unit cell but the detailed structure has not been completed because of disordering problems along the c axis. The two-dimensional structure of Re(hfac)₃ reveals C₃ symmetry and no distortion of the octahedron composed of the six Re-O bonds. Re(acac)₃ has been found to belong to the α-type isomorphous set designated by Astbury. From x-ray powder photographs, the structure of Re(acac)₃ has been demonstrated to have the same gross structural features as Mn(acac)₃ but is not necessarily isostructural. Arguments are presented to show that β-V(acac)₃ is representative of the β-modification and that the β-type isomorphous set crystallizes in a monoclinic unit cell with a β-angle of 90º. Rotational transitions between the three isomorphous sets have been examined and found to be energetically unfavourable.