AUTHOR=Goerigk Felix Christian , Locke Ralf Jules Christian , Schleid Thomas 

TITLE=Synthesis under high pressure: crystal structure and properties of cubic Dy36O11F50[AsO3]12 ∙ H2O

JOURNAL=Frontiers in Chemistry

VOLUME=Volume 12 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2024.1354690

DOI=10.3389/fchem.2024.1354690

ISSN=2296-2646

ABSTRACT=The multi-anionic compound with the composition Dy36O11F50[AsO3]12 • H2O, which can be described in the non-centrosymmetric cubic space group F4 ̅ 3c, already shows an unusually large unit cell with an axis of a = 2587.59( 14) pm. Its crystal structure exhibits isolated ψ 1 -tetrahedral [AsO3] 3-anions, but both the coordination numbers and the linking schemes of the Dy 3+ -centered polyhedra differ significantly from the mostly layered structures described so far in literature. (Dy1) 3+ is sevenfold coordinated by oxygen atoms and F -anions, forming a capped trigonal prism [(Dy1)O4.333F2.667] 8.333-and the remaining two cations (Dy2) 3+ and (Dy3) 3+ both reside eightfold coordination of anions. In both cases they form slightly distorted square antiprisms, which have the compositions of [(Dy2)O3.667F4.333] 8.667-and [(Dy3)O4.667F3.333] 9.667-, respectively. Some of the oxygen atoms are not part of ψ 1 -[AsO3] 3-tetrahedra, but occur as O 2-anions and one of those even shares a common crystallographic position with fluoride (F -). It is also worth mentioning that the single crystals were obtained as comparatively large cubes with an edge length of several 100 µm providing very good data with regard to single-crystal X-ray diffraction. To verify the simultaneous presence of oxygen and fluorine, electron-beam X-ray microprobe analysis was carried out, and a single-crystal Raman spectrum ruled out the presence of hydroxide anions or protonated [AsO3] 3-groups, but proved the interstitial crystal-water molecules, which could not be determined precisely by the crystal-structure refinement.