posted on 2023-11-09, 13:04authored byXiao Chen, Yuxiang Bu
Perfluoro-[n]prismanes ((C2F2)n, n =
3–8)
and [n]asteranes ((C3F4)n, n = 3–5) exhibit
a strong perfluoro cage effect that can stably encapsulate an additional
electron inside the cage. The 2s-like distribution of solvated electron
(esol–) not only changes the molecular structure but also affects the nuclear
spin properties. In this work, we reveal how the esol– enhances and regulates
indirect nuclear spin–spin coupling between two coupled F nuclei
(JFF-coupling). Results show that esol– is mainly
distributed in the central cavity, and a part of it penetrates into
the C-shell and C–F bond regions due to the unique polyhedral
C-shell structure. Such a 2s-like esol– creates a novel esol– based coupling mechanism,
including the newly generated through-esol– (TSE) and esol–-enhanced traditional
through-bonds and through-space (esol–-enhanced TB+TS) pathways, enhancing
and regulating N(e)JFF-coupling, which crosses N bonds in the
shortest TB pathway and is affected by esol–. The contribution of the TSE
(JTSE) is positive and increases with
the increase of the central angle between two coupled F nuclei (∠F⊗F),
and the contribution of the esol–-enhanced TB+TS (JTB+TS) is negative and |JTB+TS|
decreases with the increase of N and straight linear distance between
two coupled F nuclei (dFF). Interestingly, N(e)JFF exhibits
a special dependence on N/dFF and ∠F⊗F due to the cooperation and competition
between JTSE and JTB+TS. When ∠F⊗F < 70°, the esol–-enhanced
TB+TS can play a role; JTB+TS determines
sign and magnitude of N(e)JFF. When ∠F⊗F > 70°, the TSE dominates,
and JTSE determines sign and magnitude
of N(e)JFF. This work not only further enriches information on the states,
distributions, and properties of esol– but also provides insights into the
nuclei spin properties in perfluorinated polyhedrons triggered by
esol–.