The research of the project was carried out through four work packages (WP1–WP4). WP1 included the synthesis and single-crystal growth of novel noble-gas compounds. This package focused on the application of well-established techniques in the host laboratory: handling fluorine gas, anhydrous hydrogen fluoride, and fluorides; employing specialized synthetic experimental techniques; and utilizing low-temperature single-crystal growth methods. We synthesized a novel xenon–oxygen-bonded compound and characterized it by low-temperature single-crystal X-ray diffraction analysis, low-temperature Raman spectroscopy and quantum-chemical calculations. In addition, several possible reactions for the synthesis of novel xenon species were tested and thoroughly investigated. WP2 comprised measurements of experimental X-ray charge-density analysis of noble-gas compounds. This work package involved the use of low-temperature crystal selection and mounting techniques, as well as the measurement of high-angle, high-redundancy, low-temperature single-crystal X-ray diffraction data using a microfocus Ag Kα radiation. High-quality experimental datasets of several compounds were measured, suitable for multipole refinement. WP3 included a high-pressure study of a selected compounds in diamond anvil cells (DAC). The aim of this work package was to provide training in DAC procedures, including anvil alignment, gasket indentation, hole drilling, loading, and ruby fluorescence measurements. Training also covered DAC loading with air-sensitive compounds in a glovebox, as well as crystal structure determinations of the selected compounds under high pressure in the DAC. We successfully loaded the DAC with a main-group fluoride and measured several single-crystal X-ray diffraction datasets in the pressure range of 0.1 GPa to 4.5 GPa. The results of high-pressure crystal structure determinations research reveal an interesting effect of pressure on the intramolecular and intermolecular bonding. This work continues beyond the MSCA fellowship through ongoing collaboration between the fellow and the host laboratory. WP4 involved a secondment at Politecnico di Milano. Within this work package, training on advanced charge-density (CD) analysis and multipole refinement using the program XD2016 was conducted. This training was complemented by guidance and advising on CD experimental design, data collection, and data analysis. A detailed analysis of the bonding situation in noble-gas compounds was performed and compared with theoretical calculations.
