Noble gases, long known for their inert nature, have intrigued researchers for decades. Over 60 years ago, Neil Bartlett made a groundbreaking discovery by bonding xenon to create XePtF6, an orange-yellow solid.
However, due to challenges in crystal growth, the full potential of noble gas compounds has remained elusive.
Now, a significant breakthrough has been achieved as researchers from Jožef Stefan International Postgraduate School successfully analyzed the structures of multiple xenon compounds, shedding new light on the capabilities of these enigmatic elements. This exciting development has been reported in ACS Central Science.
Since Bartlett’s groundbreaking discovery, honored with an International Historic Chemical Landmark, numerous noble gas compounds have been produced, with some crystal structures characterized by single-crystal X-ray diffraction; however, crystals containing noble gases are usually sensitive to moisture in the air, making them highly reactive and difficult to handle. Special techniques and equipment are required to grow crystals large enough for X-ray diffraction analysis.
As a result, the detailed structures of the first xenon compound and other noble gas-containing compounds have remained elusive. Recently, a new technique called 3D electron diffraction has revealed the structures of small nanoscale crystals, which are stable in air. Although the technique hasn’t been widely used for air-sensitive compounds, researchers aim to apply 3D electron diffraction to crystallites of xenon-containing compounds.
The researchers successfully synthesized three xenon difluoride–manganese tetrafluoride compounds, resulting in the production of individual red crystals and pink crystalline powders.
To ensure the stability of the samples, a meticulous process involving the use of liquid nitrogen and multiple protective layers during the transfer into a transmission electron microscope was employed. The team utilized advanced 3D electron diffraction to measure the xenon-fluoride (Xe–F) and manganese-fluoride (Mn–F) bond lengths and angles for nanometer-sized crystallites in the pink crystalline powder.
Subsequently, the obtained structures were compared with those from single-crystal X-ray diffraction of the larger, micrometer-sized wine-red crystals. Despite minor differences, the researchers found that both methods were in good agreement. The results revealed the distinctive structures of the compounds as follows: infinite zig-zag chains for 3XeF2·2MnF4, rings for XeF2·MnF4, and staircase-like double chains for XeF2·2MnF4.
The successful demonstration of 3D electron diffraction on xenon compounds opens up new possibilities for discovering the structures of challenging noble gas compounds like XePtF6, which have evaded characterization for decades. This technique also holds promise for determining the structures of other air-sensitive substances.
Journal reference:
- Klemen Motaln, Kshitij Gurung, Petr Brázda, Anton Kokalj, Kristian Radan, Mirela Dragomir, Boris Žemva, Lukáš Palatinus, Matic Lozinšek. Reactive Noble-Gas Compounds Explored by 3D Electron Diffraction: XeF2–MnF4 Adducts and a Facile Sample Handling Procedure. ACS Central Science, 2024; DOI: 10.1021/acscentsci.4c00815