A Stable Crown Ether Complex with a Noble‐Gas Compound

Abstract

Crown ethers have been known for over 50 years, but no example of a complex between a noble‐gas compound and a crown ether or another polydentate ligand had previously been reported. Xenon trioxide is shown to react with 15‐crown‐5 to form the kinetically stable (CH2CH2O)5XeO3 adduct, which, in marked contrast with solid XeO3, does not detonate when mechanically shocked. The crystal structure shows that the five oxygen atoms of the crown ether are coordinated to the xenon atom of XeO3. The gas‐phase Wiberg bond valences and indices and the empirical bond valences indicate that the Xe‐ ‐ ‐Ocrown bonds are predominantly electrostatic and are consistent with σ‐hole bonding. Mappings of the electrostatic potential (EP) onto the Hirshfeld surfaces of XeO3 and 15‐crown‐5 in (CH2CH2O)5XeO3 and a detailed examination of the molecular electrostatic potential surface (MEPS) of XeO3 and (CH2CH2O)5 reveal regions of negative EP on the oxygen atoms of (CH2CH2O)5 and regions of high positive EP on the xenon atom, which are also in accordance with σ‐hole interactions.

Exploring Unconventional σ‐Hole Interactions: Computational Insights into the Interaction of XeO3 with Non‐Aromatic Coordinating Solvents

“…[57] This specific theoretical approach was chosen based on its established reputation for reliability, as demonstrated in benchmarks against experimentally obtained adducts of XeO 3 , by Schrobilgen's research group. [32,33] Additionally, all the stationary points were confirmed to be minima by performing harmonic frequency calculations. Furthermore, Grimme's semi-empirical Conformer-Rotamer Ensemble Sampling Tool (CREST) [58] was employed for conformational search analysis at the xTB-GFN2 levels of theory.…”

“…Optimization of each model in the gas phase was carried out by employing the APFD [56] functionals along with the def2‐TZVPD basis set [57] . This specific theoretical approach was chosen based on its established reputation for reliability, as demonstrated in benchmarks against experimentally obtained adducts of XeO 3 , by Schrobilgen's research group [32,33] . Additionally, all the stationary points were confirmed to be minima by performing harmonic frequency calculations.…”

“…detonation of XeO 3 , who were the first to experimentally verify its explosive nature, [29] brave efforts by the group of Schrobilgen in utilizing this principle led to the successful experimentally obtained stable adducts of XeO 3 with different nucleophilic molecules. [30][31][32][33] On the computational front, while there have been many studies on aerogen bonding with different types of anions, nucleophiles, crown ethers, and aromatic molecules such as benzene and its derivatives (aerogen-π interactions), [34][35][36][37][38][39][40][41] we observed a paucity in the number of detailed studies on non-aromatic coordinating solvents.…”

“…However, interestingly, the σ‐holes that are responsible for the explosive nature of XeO 3 also enable/direct other nucleophiles such as anions and Lewis bases to interact with XeO 3 , thus disrupting the Xe…O secondary interactions present in the parent XeO 3 crystal, making the newly obtained adduct of XeO 3 stable and shock‐insensitive. Considering the hospitalization of Bartlett and Rao due to the detonation of XeO 3 , who were the first to experimentally verify its explosive nature, [29] brave efforts by the group of Schrobilgen in utilizing this principle led to the successful experimentally obtained stable adducts of XeO 3 with different nucleophilic molecules [30–33] . On the computational front, while there have been many studies on aerogen bonding with different types of anions, nucleophiles, crown ethers, and aromatic molecules such as benzene and its derivatives (aerogen‐π interactions), [34–41] we observed a paucity in the number of detailed studies on non‐aromatic coordinating solvents.…”

Enabling Superprotonic Phase Transitions in Solid Acids via Supramolecular Complex Formation: The Case of Crown Ethers and Alkali Hydrogen Sulfates

“…Crown ethers have been extensively studied in the past decades for their ability to coordinate alkali and various metal ions. − Many studies on alkali metal cations coordinated to the crown ethers show how these supramolecular complexes are prone to undergoing one or more solid–solid phase transitions that may present dynamic features. ,− It has also been pointed out that the cation that is selectively captured in the crown ethers’ cavities has an explicit effect on the dynamics of these complexes. , The anhydrous supramolecular complex made up of 18-crown-6 and potassium hydrogen sulfate, 18-crown-6·KHSO 4 ( 1 ), was reported to undergo an enantiotropic solid–solid transition, which was believed, but never proved, to be associated with the onset of a dynamical process affecting the crown ether ligand and/or the hydrogen sulfate anion …”