Published by swansont on August 15, 2013 03:00 am
under Physics, Video
TBA = tert-Butyl alcohol. At the triple point, where it freezes and boils at the same time.
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High symmetry (benzene, cyclohexane… and perfluorinated) and compact (camphor, cubane) molecules pack into crystal lattices with high binding energy (high melting: C_10H_16 adamantane mp 270°C; C_8H_8 cubane with mp 131°C, octane mp -57°C ) but with low van der Waals forces (low temp boil or sublimate: cubane at room temp – not much surface area/mass). The fun one is I(CF3)_7, MW 610, melting and boiling around 0°C to the heaviest gas by far, and with no static molecular structure. Neo-pentane mp around -18°C, bp around 12°C; n-pentane mp around -130°C, bp around 36°C; n-dodecafluoropentane bp around 30°C.
Symmetric compact molecules with tight surfaces are useful. If you want to vapor-transport metals, you make the carbonyls (Fe, Ni, Mo, W), the charge-neutral hexafluoracetylacetonates, or the highest valence fluorides (PtF6, paramagnetic triplet ground state, mp 61.3°C, bp 69.14°C, and violently reactive with xenon).
Solid state C_60 C-13 NMR is the solution spectrum. Buckeyballs whizz around in their crystal lattice, lubricated by their pi-clouds. Sublimating at ~600°C, it is relatively high pressure low temp gas phase carbon, as opposed to carbon arcs or white-hot graphite.
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