MHSe: The First Hydride Selenides of the Lanthanides (M = LaNd; GdEr, Lu)

Abstract

The oxidation of most of the lanthanide dihydrides MH2 (M = LaNd; GdEr, Lu) with equimolar amounts of selenium results in the formation of the first lanthanide hydride selenides MHSe. The presence of alkali chlorides (e.g., NaCl or CsCl) as fluxes secures complete and fast reactions (7 d) at 700–850°C in sealed, arc‐welded tantalum capsules (protected by evacuated silica vessels) as well as single‐crystalline products (pale bluish‐gray hexagonal columns or platelets). Two different structures were determined from X‐ray single crystal data for the examples of 2HCeHSe (hexagonal, P63/mmc (no. 194), Z = 2, a = 406.36(4), c = 794.81(9) pm, R1 = 0.0365, wR2 = 0.0766) and 1HHoHSe (hexagonal, P6m2 (no. 187), Z = 1, a = 381.56(3), c = 387.28(5) pm, R1 = 0.0140, wR2 = 0.0337). According to X‐ray powder data, the hydride selenides MHSe with M = LaNd proved to be isostructural with 2H‐CeHSe, those with M = GdEr and Lu crystallize isotypically with 1HHoHSe just like YHSe. Both structures contain hydrogen in half of the trigonal planar interstices within closest‐packed mono‐layers of the metals. These layers ∞2[(M3+)(H−)3/3]2+ (a,β or b,α) are alternatively sheethed with closest‐packed mono‐layers of Se2− (C) along [001], and only the stacking sequence decides whether a “stuffed” WC‐ (C(a,β)C  1 H‐MHSe) or a “stuffed” anti‐NiAs‐type arrangement (C(a,β)C(b,α)C  2HMHSe) emerges.

Crystal-Structure Prediction and Experimental Investigation of the Polymorphic Lanthanum Fluoride Selenides LaFSe and La2F4Se

“…The resulting calculated structures, cell parameters, and atomic positions in the LaFSe system are presented in Table 3. correspond to known structure types: A-LaFSe crystallizes in the PbFCl-type 21 arrangement, analogous to LaFS, 6,7 the structures of B-LaFSe, C-LaFSe, and D-LaFSe are the same types as the ones of CeHSe, 11 CeHTe, 60 and LaPtSi, respectively, and La 2 F 4 Se adopts the crystal structure of Ce 2 F 4 Se 1 and La 2 H 4 Se. 12 This is not surprising considering that the commonly employed ionic radii of Se 2− and S 2− , F − and H − , and La 3+ and Ce 3+ , respectively, 62 differ by less than 10% in size.…”

“…By the formal exchange of fluorine with the next heavier congener, that is, chlorine, LaSCl 10 (crystallizing in its own unique structure type) and orthorhombic LaSeCl with the PbCl 2 -type structure emerged along with La 3 Se 4 Cl. Similarly, LaHSe (with the pseudo-halide hydrogen as H − ) is known to crystallize in the space group P6 3 /mmc, 11 isotypically with B-type LaFSe, alongside La 2 H 4 Se 12 in the trigonal La 2 F 4 Se-type structure. Furthermore, ternary selenides in combination with other highly electronegative elements, such as La 10 OSe 14 13 and La 2 O 2 Se, 14 as well as La 3 NSe 3 , 15 La 4 N 2 Se 3 , 16 La 5 NSe 6 , 17 and La 3 PSe 3 15 are found.…”

“…correspond to known structure types: A-LaFSe crystallizes in the PbFCl-type 21 arrangement, analogous to LaFS,6,7 the structures of B-LaFSe, C-LaFSe, and D-LaFSe are the same types as the ones of CeHSe,11 CeHTe,60 and LaPtSi, respectively, and La 2 F 4 Se adopts the crystal structure of Ce 2 F 4 Se 1 and La 2 H 4 Se.12 …”

Hydrogenation Reaction Pathways and Crystal Structures of La2H2Se, La2H3Se and La2H4Se

“…Analogous compounds with tellurium with the formula RE HTe crystallize in a stuffed WC type structure ( P m 2) for RE =Y, La−Nd, Gd−Er, Lu [9–11] . The analogous hydride selenides RE HSe adopt two different stuffed structure types: anti ‐NiAs type ( P 6 3 /mmc) for RE =La−Nd or WC type ( P m 2) for RE =Y, Gd−Er, Lu [12,13] . For another composition, RE 2 H 2 Se, the representatives with RE =Sc, Y, La−Nd, Gd−Lu crystallize in the Ce 2 O 2 S type structure ( m 1) [14–16] .…”

Crystal Structure and Luminescence Properties of the First Hydride Oxide Chloride with Divalent Europium: LiEu2HOCl2

“…Rare‐earth metal compounds with both hydride and chalcogenide anions are uncommon, but not unknown, as the RE HSe and RE HTe ( RE = rare‐earth elements) series demonstrates. The ternary hydride oxides RE HO for RE = La – Nd, Sm, Gd, Ho, Er as well as the quaternary lithium rare‐earth metal hydride oxides Li RE 2 HO 3 with the trivalent rare‐earth metals RE = La – Nd may serve as oxidic examples.…”