Crystal structure of tetra-kis-(1,1,1,5,5,5-hexa-fluoro-acetyl-acetonato)hafnium(IV).

ABSTRACT: The crystal structure of the title compound, [Hf(C5HF6O2)4], has been determined. The asymmetric unit contains two Hf(hfac)4 mol-ecules (hfac = 1,1,1,5,5,5-hexa-fluoro-acetyl-acetonate); both are located on general positions and have identical structures apart from the disorder involving three CF3 groups in one of the two mol-ecules. The mol-ecules 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 anti-prism. An inter-esting aspect of the structure is that the hfac ligands are arranged so that the Hf(hfac)4 mol-ecules 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-anti-prismatic geometries; in almost all of them the ligands are arranged so that the mol-ecules 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.

SUBMITTER: Schwandt WF 

PROVIDER: S-EPMC6072989 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature