03 Fakultät Chemie
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Item Open Access On the thermal dimorphy of the strontium perrhenate Sr[ReO4]2(2024) Conrad, Maurice; Bette, Sebastian; Dinnebier, Robert E.; Schleid, ThomasHygroscopic single crystals of a new hexagonal high‐temperature modification of Sr[ReO4]2 were prepared from a melt of Sr[ReO4]2 ⋅ H2O and SrCl2 ⋅ 6 H2O. The structure analysis of the obtained crystals by X‐ray diffraction revealed that the title compound crystallizes in the ThCd[MoO4]3‐type structure with the hexagonal space group P63/m and the lattice parameters a=1023.81(7) pm and c=646.92(4) pm (c/a=0.632) for Z=2 in its quenchable high‐temperature form. Two crystallographically independent Sr2+ cations are coordinated by oxygen atoms forming either octahedra or tricapped trigonal prisms, whereas the Re7+ cations are found in the centers of discrete tetrahedral meta‐perrhenate units [ReO4]-. Temperature‐dependent in‐situ PXRD studies of dry powder samples of Sr[ReO4]2 exhibited its thermal dimorphy with a phase‐transition temperature at 500-550 °C from literature‐known m‐Sr[ReO4]2 into the newly discovered h‐Sr[ReO4]2 (hexagonal).Item Open Access Syntheses and patterns of changes in structural parameters of the new quaternary tellurides EuRECuTe3 (RE = Ho, Tm, and Sc) : experiment and theory(2024) Ruseikina, Anna V.; Grigoriev, Maxim V.; Locke, Ralf J. C.; Chernyshev, Vladimir A.; Schleid, ThomasThe layered orthorhombic quaternary tellurides EuRECuTe3 (RE = Ho, Tm, Sc) with Cmcm symmetry were first synthesized. Single crystals of the compounds up to 500 μm in size were obtained by the halide-flux method at 1120 K from elements taken in a ratio of Eu/RE/Cu/Te = 1:1:1:3. In the series of compounds, the changes in lattice parameters were in the ranges a = 4.3129(3)-4.2341(3) Å, b = 14.3150(9)-14.1562(9) Å, c = 11.2312(7)-10.8698(7) Å, V = 693.40(8)-651.52(7) Å3. In the structures, the cations Eu2+, RE3+ (RE = Ho, Tm, Sc), and Cu+ occupied independent crystallographic positions. The structures were built with distorted copper tetrahedra forming infinite chains [CuTe4]7− and octahedra [RETe6]9- forming two-dimensional layers along the a-axis. These coordination polyhedra formed parallel two-dimensional layers CuRETe32-∞2. Between the layers, along the a-axis, chains of europium trigonal prisms [EuTe6]10- were located. Regularities in the variation of structural parameters and the degree of distortion of coordination polyhedra depending on the ionic radius of the rare-earth metal in the compounds EuRECuCh3 (RE = Ho, Er, Tm, Lu, Sc; Ch = S, Se, Te) were established. It is shown that with a decrease in the ionic radius ri(RE3+) in the compounds EuRECuTe3, the unit-cell volume, bond length d(RE-Te), distortion degree [CuTe4]7-, and crystallographic compression of layers [RECuTe3]2- decreased. The distortion degree of tetrahedral polyhedra [CuCh4]7-, as well as the structural parameters in europium rare-earth copper tellurides EuRECuTe3, were higher than in isostructural quaternary chalcogenides. Ab initio calculations of the crystalline structure, phonon spectrum, and elastic properties of compounds EuRECuTe3 (RE = Ho, Tm, and Sc) ere conducted. The types and wave numbers of fundamental modes were determined, and the involvement of ions in IR and Raman modes was assessed. The calculated data of the crystal structure correlated well with the experimental results.Item Open Access The first members of the monoclinic lanthanoid(III) fluoride oxoarsenate(III) series Ln2F2[As2O5] (Ln=La - Nd and Sm)(2025) Locke, Ralf J. C.; Zimmer, Frank C.; Schleid, ThomasIn synthesis experiments for the preparation of Ln5F3[AsO3]4 representatives in evacuated glassy silica ampoules at temperatures of maximum 825 °C, surprisingly compounds with the composition Ln2F2[As2O5] could be obtained and subsequently also reproduced on target. The new Ln2F2[As2O5] representatives with Ln = La - Nd and Sm crystallize needle‐shaped in the monoclinic space group P21/c with lattice parameters ranging from a = 793.24(5) pm, b = 1346.39(9) pm, c = 1359.41(9) pm and β = 106.932(3)° for La2F2[As2O5] to a = 769.11(5) pm, b = 1307.50(9) pm, c = 1328.74(9) pm and β = 106.819(3)° for Sm2F2[As2O5] with Z = 8. Their crystal structure can be broken down into two parts consisting of infinite [Ln2F2]4+ and discrete [As2O5]4− units. Three distinct kinds of fluoride anions are trigonally planar surrounded by lanthanoid cations and another one carries even a fourth of them in their coordination sphere with a secondary contact resulting in a distorted tetrahedron. These [FLn3]8+ and [FLn3+1]11+ building blocks share common corners and edges creating strands {[F2Ln2]4+}, which propagate along [100]. The four different As3+ lone‐pair cations form ψ1‐tetrahedra [AsO3]3− with three oxygen atoms and are conversurally linked pairwisely creating dinuclear pyroanionic [As2O5]4− units. These [As2O5]4− groups arrange themselves alternatingly along [100] with their lone pairs pointing into central empty channels. The {[F2Ln2]4+} strands are linked to the [As2O5]4− units via four distinguishable Ln3+ cations providing them coordination numbers of eight and nine. Raman spectroscopy confirmed that no (OH)− groups resulting from the synthesis were present apt to replace part of the F− and the stoichiometry Ln2F2[As2O5] was verified using WDXS elemental analyses.Item Open Access Ba7C2Al2O9 : a barium oxide carbide oxoaluminate with the structured formula Ba7O[C2][AlO4]2(2025) Reckeweg, Olaf; Lissner, Falk; Locke, Ralf J. C.; Schleid, ThomasThe mixed‐anionic barium compound Ba7O[C2][AlO4]2 is obtained by serendipity via a high‐temperature synthesis route designed to yield “Ba5[AlC2]2”. Its new crystal structure is determined from X‐ray diffraction data of selected single crystals exhibiting the orthorhombic space group Pnma with the lattice parameters a = 2264.21(16), b = 597.08(4), and c = 1114.67(8) pm for Z = 4. Isolated [AlO4]5- tetrahedra alongside O2- and [C2]2- anions provide appropriate coordination spheres for the seven crystallographically independent Ba2+ cations with C.N. = 7-9. These structural elements and their incremental volumes are compared to those of related compounds. Irregular [OBa5+1]10+ octahedra and ([C2]Ba5+2)12+ polyhedra complete the crystal structure of Ba7O[C2][AlO4]2, whose most covalent features (ortho‐oxoaluminate tetrahedra [AlO4]5- and acetylide dumbbells -[C≡C]-) can also be identified unambiguously by single‐crystal Raman spectroscopy.Item Open Access On the rubidium thiotellurate(IV) Rb2[TeS3] and its tritohydrate Rb2[TeS3] ⋅ 1/3 H2O(2024) Wolff, Klaus K.; Pfitzner, Arno; Schleid, ThomasRb2[TeS3] and Rb2[TeS3] ⋅ 1/3 H2O were obtained from rubidium azide (RbN3), tellurium and sulfur in 2 : 1 : 3 molar ratios from evacuated fused silica ampoules at 500 °C under more or less anhydrous conditions. Both compounds crystallize orthorhombically in the space group P212121 (Rb2[TeS3]: a=873.42(6) pm, b=1316.73(9) pm, c=2064.59(14) pm; Rb2[TeS3] ⋅ 1/3 H2O: a=872.97(6) pm, b=1299.82(9) pm, c=2148.26(15) pm, both at -173 °C for Z =12) and contain discrete ψ1‐tetrahedral [TeS3]2- anions (d(Te-S)=232-236 pm) in layerwise arrangements. The difference results from the water of hydration in Rb2[TeS3] ⋅ 1/3 H2O, which increases the coordination numbers of half of the six crystallographically distinct Rb+ cations from six and seven (only sulfur) to seven and almost eight by providing with oxygen from H2O an extra ligand (d(Rb-O)=290-318 pm). Red Rb2[TeS3] transforms pseudo‐topotactically into yellow Rb2[TeS3] ⋅ 1/3 H2O immediately upon contact with moist atmosphere. The compounds were screened with X‐ray diffraction, Raman and diffuse reflectance spectroscopy as well as thermal analysis.Item Open Access Synthesis under high pressure : crystal structure and properties of cubic Dy36O11F50[AsO3]12 ∙ H2O(2024) Goerigk, Felix Christian; Locke, Ralf Jules Christian; Schleid, ThomasThe multi-anionic compound with the composition Dy36O11F50[AsO3]12 ∙ H2O, which can be described in the non-centrosymmetric cubic space group F-43c, already shows an unusually large unit cell with an axis of a = 2587.59(14) pm. Its crystal structure exhibits isolated ψ1-tetrahedral [AsO3]3- anions, but both the coordination numbers and the linking schemes of the Dy3+-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 in an 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 ψ1-[AsO3]3- tetrahedra, but occur as O2- anions and one of these 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 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.Item Open Access Ytterbium(III) tricyanomethanides with sodium and potassium : similarities and differences between NaYb[C(CN)3]4 and KYb[C(CN)3]4(2025) Locke, Ralf J. C.; Montana, Giuseppe; Stelzer, Robert U.; Emminghaus, Anahita I. A.; Lissner, Falk; Reckeweg, Olaf; Schleid, Thomas; Wickleder, ClaudiaMetathesis reactions of Ag[C(CN)3] with anhydrous YbCl3 dissolved in water combined with stoichiometric amounts of the alkali-metal salts A[C(CN)3] (A = Na or K) yield the non-isotypic tetragonal compounds NaYb[C(CN)3]4 (P4/nnc with a = 1188.37(9) pm, c = 1232.41(9) pm) and KYb[C(CN)3]4 (P4/nbm with a = 1179.26(9) pm, c = 668.73(5) pm). Both crystal structures contain a three-dimensional framework (Niggli formula: 3∞{(Yb[C(CN)3]8/2)-}) with Yb3+ in square antiprismatic coordination of terminal nitrogen atoms (d(Yb-N) = 241-242 pm) from eight planar star-shaped tricyanomethanide anions [C(CN)3]-. The Na+ or K+ cations occupy vacancies, which provide them with a tetrahedral coordination sphere of nitrogen (d(Na-N) = 239 pm vs. d(K-N) = 276 pm) from four [C(CN)3]- anions. This difference results from secondary contacts with the central carbon atoms (d(Na-C) = 361 pm vs. d(K-C) = 367 pm) of four different [C(CN)3]- units, which do not contribute to NaYb[C(CN)3]4, but effectuate a lot in the case of KYb[C(CN)3]4. The Raman spectrum recorded for NaYb[C(CN)3]4 corroborates the presence of a pseudo-D3h-symmetric tricyanomethanide anion [C(CN)3]- and the absence of water.Item Open Access Synthesis, crystal structure, and optical and magnetic properties of the new quaternary erbium telluride EuErCuTe3 : experiment and calculation(2024) Ruseikina, Anna V.; Grigoriev, Maxim V.; Locke, Ralf J. C.; Chernyshev, Vladimir A.; Garmonov, Alexander A.; Schleid, ThomasThis paper reports for the first time on a new layered magnetic heterometallic erbium telluride EuErCuTe3. Single crystals of the compound were obtained from the elements at 1120 K using CsI as a flux. The crystal structure of EuErCuTe3 was solved in the space group Cmcm (a = 4.3086(3) Å, b = 14.3093(9) Å, and c = 11.1957(7) Å) with the KZrCuS3 structure type. In the orthorhombic structure of erbium telluride, distorted octahedra ([ErTe6]9−) form two-dimensional layers (Er(Te1)2/2e(Te2)4/2k-)∞2, while distorted tetrahedra ([CuTe4]7-) form one-dimensionally connected substructures (Cu(Te1)2/2e(Te2)2/1t5-∞1) along the [100] direction. The distorted octahedra and tetrahedra form parallel two-dimensional layers (CuErTe32-∞2) between which Eu2+ ions are located in a trigonal-prismatic coordination environment (EuTe610-). The trigonal prisms are connected by faces, forming chains (Eu(Te1)2/2(Te2)4/22-∞1) along the [100] direction. Regularities in the variations in structural parameters were established in the series of erbium chalcogenides (EuErCuCh3 with Ch = S, Se, and Te) and tellurides (EuLnCuTe3 with Ln = Gd, Er, and Lu). Ab-initio calculations of the crystal structure, phonon spectrum, and elastic properties of the compound EuErCuTe3 were performed. The types and wavenumbers of fundamental modes were determined, and the involvement of ions in the IR and Raman modes was assessed. The experimental Raman spectra were interpreted. The telluride EuErCuTe3 at temperatures below 4.2 K was ferrimagnetic, as were the sulfide and selenide derivatives (EuErCuCh3 with Ch = S and Se). Its experimental magnetic characteristics were close to the calculated ones. The decrease in the magnetic phase transition temperature in the series of the erbium chalcogenides was discovered.Item Open Access Two new energetic hexagonal anti-perovskites (N2H5)3X[B12H12] · H2O (X- = [NO3]- and [ClO4]-) : crystal structure, vibrational spectra, and thermal decomposition(2024) Aghaei Hakkak, Rouzbeh; Klapötke, Thomas M.; Schleid, ThomasTwo novel energetic anti-perovskite compounds with the chemical formula (N2H5)3X[B12H12] · H2O, where X- is either [NO3]− or [ClO4]−, were successfully synthesized. Both dodecahydro-closo-dodecaborates crystallize orthorhombically in the space group Cmc21, exhibiting relatively similar lattice parameters ((N2H5)3[NO3][B12H12] · H2O: a = 915.94(5), b = 1817.45(9), c = 952.67(5) pm, (N2H5)3[ClO4][B12H12] · H2O: a = 1040.51(6), b = 1757.68(9), c = 942.34(5) pm both for Z = 4). Their synthesis involved a two-step process: first, Cs2[B12H12] passed through a cation exchange column to yield the acidic form of the dodecahydro-closo-dodecaborate, (H3O)2[B12H12]. This aqueous solution was subsequently neutralized with hydrazinium hydroxide and mixed with the corresponding water-dissolved hydrazinium salt (nitrate or perchlorate). Characterization of the obtained crystals was performed by single-crystal X-ray diffraction and Raman spectroscopy as well as thermal analyses (TG-DTA and DSC). The crystal structure determinations revealed that both compounds adopt a hexagonal anti-perovskite structure, distorted by the presence of water molecules. These compounds containing oxidizing oxoanions demonstrate a remarkable ability to release large amounts of energy (almost 2100 J/g) upon thermal decomposition.Item Open Access La11Si11P21Te5 and La20.667Si18P46Te11.333 : two novel 3D‐polyanionic lanthanum compounds following the Zintl‐Klemm concept(2024) Djendjur, Patrik; Anschütz, Zoë A.; Niewa, Rainer; Schleid, ThomasDuring attempts to synthesize La3PTe3, after participation of the SiO2-container material, two so far unknown compounds could be isolated, which both follow the Zintl-Klemm concept. The novel quaternary lanthanum tellurides La11Si11P21Te5 and La20.667Si18P46Te11.333 crystallize hexagonally in the non-centrosymmetric space group Pmathematical equation c with the unit-cell parameters a=1204.97(6)-pm and c=1802.38(9)-pm (c/a=1.496) or a=1205.78(6)-pm and c=1802.16(9)-pm (c/a=1.495), respectively. Their very similar crystal structures can be divided into two interpenetrating three-dimensional sublattices, mathematical equation {[La11Te5]23+} (d(La3+-Te2-)=314-335-pm plus 352-pm) and mathematical equation {[Si11P21]23-} (d(Si-P)=221-225-pm, d(Si-Si)=230-231-pm, d(P-P)=220-221-pm) for La11Si11P21Te5 (Z=2), displaying unique structural features as compared to related compounds. The linkage of these two sublattices occurs through attractive La3+-Si- and La3+-P- interactions (d(La-Si)=333-pm, d(La-P)=298-318-pm). For La20.667Si18P46Te11.333 (Z=1), 4/3 out of 22 La3+cations in the doubled formula La22Si22P42Te10 have to be omitted, while the four Si- anions need to be replaced with phosphorus atoms. The La3+ vacancies are filled up with tellurium, partly forming [Te2]2- dumbbells (d(Te-Te)=274-pm). La11Si11P21Te5 can be obtained on target by reacting the elements (La, Si, P and Te) in their respective amounts with an excess of potassium chloride as fluxing agent in evacuated and torch-sealed glassy silica ampoules for four days at 900 °C as black pillars or thick plates with hexagonal cross-section.