The recently reported synthesis[1] of octafluorocubane established a sublimation point as 168.1–177.1°C (a melting point was not observed). In contrast, the heavier perfluoro-octane has an m.p. of -25°C. Why the difference? Firstly, the crystal structure is shown below, albeit as a dimer rather than a periodic lattice (click on image to obtain 3D coordinates).
References
- M. Sugiyama, M. Akiyama, Y. Yonezawa, K. Komaguchi, M. Higashi, K. Nozaki, and T. Okazoe, "Electron in a cube: Synthesis and characterization of perfluorocubane as an electron acceptor", Science, vol. 377, pp. 756-759, 2022. http://dx.doi.org/10.1126/science.abq0516