What is the structure of the hypothetical xenon octafluoride? According to Frlec et al.,[1] theoretical studies indicated that there is a possibility (albeit slim) that neutral xenon octafluoride ($\ce{XeF8}$) might exist.

I am curious as to what structure this molecule might possibly have. In terms of hybridisation theory, I have only learnt cases up to seven-coordination ($\mathrm{d^3sp^3}$ or $\mathrm{sp^3d^3}$), where the molecular geometry is pentagonal bipyramidal. However, answers based on other frameworks (e.g. molecular orbital theory) would also be welcome.

My conjecture: could its structure possibly be hexagonal bipyramidal?


Frlec, B.; Holloway, J. H.; Slivnik, J.; Šmalc, A.; Volavšek, B.; Zemljič, A. An examination of the possibility of the existence of xenon octafluoride. J. Inorg. Nucl. Chem. 1970, 32 (8), 2521–2527. DOI: 10.1016/0022-1902(70)80296-2.
There does seem to be a good body of evidence, including your reference, for the existence of xenon octafluoride.

Regarding it's structure, according to VSEPR theory as tabulated here, the structure is square anti prism: