Crystal structure of tetra­kis­(1,1,1,5,5,5-hexa­fluoro­acetyl­acetonato)hafnium(IV)

The crystal structure of the title compound, [Hf(C(5)HF(6)O(2))(4)], has been determined. The asymmetric unit contains two Hf(hfac)(4) mol­ecules (hfac = 1,1,1,5,5,5-hexa­fluoro­acetyl­acetonate); both are located on general positions and have identical structures apart from the disorder involving three CF(3) groups in one of the two mol­ecules. The mol­ecules of Hf(hfac)(4) are arranged in layers that are parallel to the ab plane, and the coordination geometry of each hafnium(IV) center is a distorted square anti­prism. An inter­esting aspect of the structure is that the hfac ligands are arranged so that the Hf(hfac)(4) mol­ecules have idealized 2 point symmetry, in which two of the hfac groups bridge between the two squares. Although all other M(β-diketonate)(4) compounds of Hf (and Zr) also have square-anti­prismatic geometries; in almost all of them the ligands are arranged so that the mol­ecules have 222 point symmetry (in which none of the hfac ligands bridges between the two squares). The factors that favor one structure over another are not clear.