The Perfluoro Cage Effect: A Search For Electron-Encapsulating Molecules

08 November 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Quantum chemical calculations have for some time predicted that perfluorinated polyhedral organic molecules should exhibit a low-energy LUMO consisting av the overlapping inward-pointing lobes of the C-F * orbitals. Accordingly, they should be able to encapsulate an electron within the interior of their cavities. Inspired by the recent confirmation of this prediction for octafluorocubane, we have sought to identify additional perfluorinated cage molecules capable of this remarkable behavior, which we refer to as the perfluoro cage effect (PCE). Using DFT calculations with multiple well-tested exchange-correlation functionals and large STO-QZ4P basis sets, we have successfully identified several systems including [n]prismanes (n = 3-6), [n]asteranes (n = 3-5), twistane, and two norbornadiene dimer cages that clearly exhibit the PCE. In other words, they exhibit a low-energy LUMO belonging to the total symmetric irrep of the point group in question and adiabatic electron affinities ranging from somewhat under 1 eV to over 2 eV. A pronounced size effect appears to hold, with larger cages exhibiting higher EAs. The largest adiabatic EAs, well over 3 eV, are predicted for perfluorinated dodecahedrane and C60. In contrast, the PCE is barely discernible for perfluorinated tetrahedrane and bicyclo[1.1.1]pentane.

Keywords

cage molecules
polyhedral molecules
electron affinity
carcerand. cubane
prismane
asterane
twistane
adamantane

Supplementary materials

Title
Description
Actions
Title
Optimized Cartesian coordinates (22 pages)
Description
Optimized all-electron B3LYP*/STO-QZ4P coordinates (Å)
Actions

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