Bonding in Uranium(V) Hexafluoride Based on the Experimental Electron Density Distribution Measured at 20 K

The electron density distribution
of [PPh4]­[UF6] was obtained from high-resolution
X-ray diffraction data measured at 20 K. The electron density was
modeled with an augmented Hansen–Coppens multipolar formalism.
Topological analysis reveals that the U–F bond is of incipient
covalent nature. Theoretical calculations add further support to the
bonding description gleaned from the experimental model. The impact
of the uranium anomalous dispersion terms on the refinement is also
discussed.