Electron-Diffraction Investigation of the Hexafluorides of Tungsten, Osmium, Iridium, Uranium, Neptunium, and Plutonium

An electron‐diffraction investigation has been made by the sector–microphotometer method on WF₆, OsF₆, IrF₆, UF₆, NpF₆, and PuF₆. The photographs of all these compounds reflect a phase shift which if not accounted for leads to asymmetric structures for the molecules. It sets in at smaller values of ${\text{s\hspace{0.17em}=\hspace{0.17em}4πλ}}^{\text{−1}}\sin \text{(θ\hspace{0.17em}/\hspace{0.17em}2)}$ the heavier the molecule and the greater the electron wavelength. There is good evidence for the symmetrical octahedral structure of all the compounds. The metal–fluorine distances were found to be 1.833 Å (W–F), 1.831 Å (Os–F), 1.830 Å(Ir–F), 1.996 Å (U–F), 1.981 Å (Np–F), and 1.971 Å (Pu–F), with estimated limits of error of ±0.008 Å except for ±0.010 Å for Pu–F.