Prediction of stable radon fluoride molecules and geometry optimization using first-principles calculations

Abstract

Noble gases possess extremely low reactivity because their valence shells are closed. However, previous studies have suggested that these gases can form molecules when they combine with other elements with high electron affinity, such as fluorine. Radon is a naturally occurring radioactive noble gas, and the formation of radon-fluorine molecules is of significant interest owing to its potential application in future technologies that address environmental radioactivity. Nevertheless, because all isotopes of radon are radioactive and the longest radon half-life is only 3.82 days, experiments on radon chemistry have been limited. Here, we study the formation of radon molecules using first-principles calculations; additionally, possible compositions of radon fluorides are predicted using a crystal structure prediction approach. Similar to xenon fluorides, di-, tetra-, and hexafluorides are found to be stabilized. Coupled-cluster calculations reveal that RnF6 stabilizes with Oh point symmetry, unlike XeF6 with C3v symmetry. Moreover, we provide the vibrational spectra of our predicted radon fluorides as a reference. The molecular stability of radon di-, tetra-, and hexafluoride obtained through calculations may lead to advances in radon chemistry.

Student perceptions of partial charges and nucleophilicity/electrophilicity when provided with either a bond-line, ball-and-stick, or electrostatic potential map for molecular representation

“…Practicing chemists generate EPMs from experimental data and use the resulting model to detect high reactivity within a molecule. Examples of this are included in the popular journal Nature in which several articles were published using EPMs during the year this paper was written (Jain et al, 2023;Kang et al, 2023;Shalaby et al, 2023). Being able to interpret and utilize EPMs is becoming an essential skill of a practicing chemist and should be considered as a part of student training.…”

The inert pair effect on heavy noble gases: insights from radon tetroxide

“…Fitzsimmons and Klobukowski 11 examined a family of organic xenon and radon fluorides and showed that Rn species were thermodynamically more stable than the Xe congeners. Recently, a study has been published by Um and coworkers 12 where their best estimation of the formation enthalpy for RnF 6 was −584 kJ mol −1 , whereas for XeF 6 , the value was −264 kJ mol −1 . In contrast to the oxides, it appears that the fluorides of radon and xenon are generally exergonic.…”

“…The chemistry of radon may be rich and varied, and there are promising indications [7][8][9][10][11][12] that this is the case. Fitzsimmons and Klobukowski 11 examined a family of organic xenon and radon fluorides and showed that Rn species were thermodynamically more stable than the Xe congeners.…”

“…6 However, the vast majority of recent works on radon compounds has been in silico. [7][8][9][10][11][12] The highest formal oxidation state in the noble gas group is VIII, as exemplified by xenon tetroxide, an explosive gas identified by Selig et al 13 and structurally characterized by electron diffraction few years later by Gundersen et al 14 Its explosive character accounts for its high endothermicity 15 (D f H 298 K = +642 kJ mol À1 ). Slepkov et al 16 performed a detailed DFT study of the potential energy surface of XeO 4 and predicted the existence of a short lived isomer Xe(Z 2 -O 2 ) 2 that would act as an intermediate in the decomposition reaction.…”

Chemical Aristocracy: He3 Dication and Analogous Noble-Gas-Exclusive Covalent Compounds

“…Fluorine, characterized by its remarkably high IP, can offset the excitation energy of noble gas electronic configurations, allowing for the formation of noble-gas fluorides. Indeed, species such as KrF 2 , XeF 2 , and RnF 2 are among the most renowned compounds involving noble gases . Notably, they represent a rare category of symmetric insertion compounds with noble gases, with RnF 2 being the only radon compound experimentally reported.…”