03 Fakultät Chemie

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Open Access
Synthesis, crystal structure and properties of the new laminar quaternary tellurides SrLnCuTe3 (Ln = Sm, Gd-Tm and Lu)
(2023) Ruseikina, Anna V.; Grigoriev, Maxim V.; Molokeev, Maxim S.; Garmonov, Alexander A.; Elyshev, Andrey V.; Locke, Ralf J. C.; Schleid, Thomas
This paper reports for the first time on the new laminar quaternary orthorhombic heterometallic quaternary tellurides SrLnCuTe3, the fabrication of which has been a challenge until this work. Data on the crystal structure of tellurides complete the series of quaternary strontium chalcogenides SrLnCuCh3 (Ch = S, Se, Te). Single crystals of the compounds were synthesized from the elements by the halogenide-flux method at 1070 K. The compounds are crystallizing in two space groups Pnma (Ln = Sm, Gd and Tb) and Cmcm (Ln = Dy-Tm and Lu). For SrSmCuTe3 (a = 11.4592(7), b = 4.3706(3), c = 14.4425(9) Å, space group: Pnma) with the largest lanthanoid cation, Sr2+ shows C.N. = 7, whereas Sm3+ reveals a diminished coordination number C.N. = 6. For SrLuCuTe3 (a = 4.3064(3), b = 14.3879(9), c = 11.1408(7) Å, space group: Cmcm) with the smallest lanthanoid cation, coordination numbers of six are realized for both high-charged cations (Sr2+ and Lu3+: C.N. = 6). The cations Sr2+, Ln3+, Cu+ each take independent positions. The structures are built by distorted [CuTe4]7- tetrahedra, forming the infinite chains {∞1[Cu(Te1)1/1t(Te2)1/1t(Te3)2/2e]5−} along [010] in SrLnCuTe3 (Ln = Sm, Gd and Tb) and [100] in SrLnCuTe3 (Ln = Dy-Tm and Lu). The distortion of the polyhedra [CuTe4]7- was compared for the whole series SrLnCuTe3 by means of τ4-descriptor for the four coordinating Te2- anions, which revealed a decrease in the degree of distortion with a decreasing radius at Ln3+. The distorted octahedra [LnTe6]9- form layers {∞2[Ln(Te1)2/2(Te2)2/2(Te3)2/2]3−}. The distorted octahedra and tetrahedra fuse to form parallel layers {∞2[CuLnTe3]2−} and between them, the Sr2+ cations providing three-dimensionality of the structure are located. In the SrLnCuTe3 (Ln = Sm, Gd and Tb) structures, the Sr2+ cations center capped the trigonal prisms [SrTe6+1]12−, united in infinite chains {∞1[Sr(Te1)2/2(Te2)3/3(Te3)2/2]4−} along the [100] direction. The domains of existence of the Ba2MnS3, BaLaCuS3, Eu2CuS3 and KZrCuS3 structure types are defined in the series of orthorhombic chalcogenides SrLnCuCh3 (Ch = S, Se and Te). The tellurides SrLnCuTe3 (Ln = Tb-Er) of both structure types in the temperature range from 2 up to 300 K are paramagnetic, without showing clear signs of a magnetic phase transition.
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, Thomas
In 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.
Open Access
Sulfur‐composites derived from poly(acrylonitrile) and poly(vinylacetylene) : a comparative study on the role of pyridinic and thioamidic nitrogen
(2023) Kappler, Julian; Klostermann, Sina V.; Lange, Pia L.; Dyballa, Michael; Veith, Lothar; Schleid, Thomas; Weil, Tanja; Kästner, Johannes; Buchmeiser, Michael R.
Sulfurized poly(acrylonitrile) (SPAN) is a prominent example of a highly cycle stable and rate capable sulfur/polymer composite, which is solely based on covalently bound sulfur. However, so far no in‐depth study on the influence of nitrogen in the carbonaceous backbone, to which sulfur in the form of thioketones and poly(sulfides) is attached, exists. Herein, we investigated the role of nitrogen by comparing sulfur/polymer composites derived from nitrogen‐containing poly(acrylonitrile) (PAN) and nitrogen‐free poly(vinylacetylene) (PVac). Results strongly indicate the importance of a nitrogen‐rich, aromatic carbon backbone to ensure full addressability of the polymer‐bound sulfur and its reversible binding to the aromatic backbone, even at high current rates. This study also presents key structures, which are crucial for highly cycle and rate stable S‐composites.
Open Access
On the rubidium thiotellurate(IV) Rb2[TeS3] and its tritohydrate Rb2[TeS3] ⋅ 1/3 H2O
(2024) Wolff, Klaus K.; Pfitzner, Arno; Schleid, Thomas
Rb2[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.
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, Thomas
The 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.
Open Access
Luminescence properties of Y3F[Si3O10]:Ln3+ (Ln = Eu, Tb, Er) with thalenite-type host lattice and crystal structure of Tm3F[Si3O10]
(2023) Schäfer, Marion C.; Petter, Michael; Hartenbach, Ingo; Locke, Ralf J. C.; Zhang, Shuang; Wickleder, Claudia; Schleid, Thomas
With Tm3F[Si3O10], a new representative of the Ln3F[Si3O10] series could be synthesized by the reaction of Tm2O3, TmF3 and SiO2 (molar ratio: 1:1:3), applying an excess of CsBr as a fluxing agent in gas-tightly sealed platinum crucibles for eight days at 750 °C, and designed to yield Tm3F3[Si3O9] or Cs2TmF[Si4O10]. Single crystals of Tm3F[Si3O10] (monoclinic, P21/n; a = 725.04(6), b = 1102.43(9), c = 1032.57(8) pm, β = 97.185(7)°; Z = 4) appear as pale celadon, transparent, air- and water-resistant rhombic plates. According to its thalenite-type structure, Tm3F[Si3O10] contains catena-trisilicate anions [Si3O10]8− and triangular [FTm3]8+ cations. The three crystallographically different Tm3+ cations are coordinated by seven plus one (Tm1) or only seven anions (Tm2 and Tm3) exhibiting a single F- anion for each polyhedron, additional to the majority of O2- anions. Furthermore, the luminescence properties of the isotypic colorless compound Y3F[Si3O10] doped with Eu3+ (red emission), Tb3+ (green emission) and Er3+ (yellow and infrared emission), respectively, are reported in presenting their different excitation and emission spectra.
Open Access
On the thermal dimorphy of the strontium perrhenate Sr[ReO4]2
(2024) Conrad, Maurice; Bette, Sebastian; Dinnebier, Robert E.; Schleid, Thomas
Hygroscopic 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).
Open Access
Li4Ln[PS4]2Cl : chloride-containing lithium thiophosphates with lanthanoid participation (Ln = Pr, Nd and Sm)
(2023) Lange, Pia L.; Bette, Sebastian; Strobel, Sabine; Dinnebier, Robert E.; Schleid, Thomas
The synthesis and structural analysis of three new chloride-containing lithium thiophosphates(V) Li4Ln[PS4]2Cl with trivalent lanthanoids (Ln = Pr, Nd and Sm) are presented and discussed. Single crystals of Li4Sm[PS4]2Cl were obtained and used for crystal structure determination by applying X-ray diffraction. The other compounds were found to crystallize isotypically in the monoclinic space group C2/c. Thus, Li4Sm[PS4]2Cl (a = 2089.31(12) pm, b = 1579.69(9) pm, c = 1309.04(8) pm, β = 109.978(3)°, Z = 12) was used as a representative model to further describe the crystal structure in detail since Li4Pr[PS4]2Cl and Li4Nd[PS4]2Cl were confirmed to be isotypic using powder X-ray diffraction measurements (PXRD). In all cases, a trigonal structure in the space group R3̲ (e.g., a = 1579.67(9) pm, c = 2818.36(16) pm, c/a = 1.784, Z = 18, for Li4Sm[PS4]2Cl) displaying almost identical building units worked initially misleadingly. The structure refinement of Li4Sm[PS4]2Cl revealed bicapped trigonal prisms of sulfur atoms coordinating the two crystallographically distinct (Sm1)3+ and (Sm2)3+ cations, which are further coordinated by four anionic [PS4]3- tetrahedra. The compounds also contain chloride anions residing within channel-like pores made of [PS4]3- units. Eight different sites for Li+ cations were identified with various coordination environments (C.N. = 4-6) with respect to chlorine and sulfur. EDXS measurements supported the stoichiometric formula of Li4Ln[PS4]2Cl, and diffuse reflectance spectroscopy revealed optical band gaps of 2.69 eV, 3.52 eV, and 3.49 eV for Li4Sm[PS4]2Cl, Li4Nd[PS4]2Cl, and Li4Pr[PS4]2Cl, respectively. The activation energy for Li+-cation mobility in Li4Sm[PS4]2Cl was calculated as Ea(Li+) = 0.88 eV using BVEL, which indicates potential as a Li+-cation conductor.
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, Claudia
Metathesis 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.
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, Thomas
During 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.

03 Fakultät Chemie

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