Although the demonstration of noble-gas reactivity represents one of the most significant breakthroughs of 20th-century inorganic chemistry, the first noble-gas compound, XePtF6 (XeF2·PtF4), lacks comprehensive structural characterization, and its structure remains to be elucidated. In this study, the XeF2-PtF4 and XeF2-PdF4 systems were reexplored, resulting in the crystal structure determination of XeF2·2PtF4 and XeF2·2PdF4 by 3D electron diffraction, marking the first successful structural characterization of compounds from these systems. Both compounds are isostructural with the previously characterized XeF2·2MnF4, featuring corrugated zigzag double-chain motifs formed by interconnected octahedral fluoridometallate(IV) units. Periodic density functional theory calculations were employed to evaluate the structural models of XeF2·PtF4, which were derived from experimentally determined crystal structures of XeF2-MF4 (M = Cr, Mn) analogues. The results reveal a preference for cis-bridging between adjacent platinum(IV) centers and show that a tetrameric ring structure and cis-chain polymorph, modeled after the crystal structure of XeF2·MnF4 and XeF2-deficient 3XeF2·2MnF4, respectively, emerge as energetically favored. The results of this study thus provide a direct structural link between platinum, palladium, and manganese analogues in the XeF2-MF4 systems and highlight the tetrameric ring structure and cis-chain as likely structural models of XeF2·PtF4.

• Publication type
• Journal Article MeSH

The accurate characterization of highly sensitive materials using 3D electron diffraction (3D ED) is often challenged by sample degradation caused by exposure to moisture, air, temperature variations and high vacuum during the transfer and introduction into the transmission electron microscope (TEM). A cryogenic sample-transfer protocol is presented here, designed to enable the safe and effective transfer of reactive samples into the TEM, ensuring an inert and moisture-free environment throughout the process. The protocol was validated by redetermining the crystal structures of the moisture-sensitive, strongly oxidizing and highly reactive compounds XeF2, XeF4 and XeF2·XeF4 cocrystal. Crystal structures of all three compounds were successfully solved ab initio and dynamically refined, yielding results that showed good agreement with the previously reported X-ray and neutron diffraction structures. This approach holds significant promise for advancing the study of other reactive and moisture-sensitive samples, enabling precise structural characterization in cases where traditional TEM sample preparation is unsuitable.

• Keywords
• 3D electron diffraction, cryotransfer, noble-gas compounds, xenon fluorides,
• Publication type
• Journal Article MeSH