Kristallstrukturen von Verbindungen A2[MnF3(SO4)] (A = Rb,NH4, Cs): Jahn‐Teller‐Ordnung in Mangan(III)‐fluoridsulfaten. I.

Jahn‐Teller Ordering in Manganese(III) Fluoride Sulphates. I. Crystal Structures of A₂[MnF₃(SO₄)] (A = Rb, NH4, Cs) The three isostructural fluorosulphatomanganates(III) A₂[MnF₃(SO₄)] (A = Rb, NH₄, Cs) crystallize in space group P2₁/c, Z = 4. Rb₂[MnF₃(SO₄)]: a = 7.271, b = 11.091, c = 8.776Å, β = 92.26°, R = 0.033; (NH₄)₂[MnF₃(SO₄)]: a = 7.299, b = 10.157, c = 8.813Å, β = 91.51°, R = 0.025; Cs₂[MnF₃(SO₄)]: a = 7.365, b = 11.611, c = 9.211, β = 92.30°, R = 0.029. In the chain anions [MnF₃(SO₄)]^2— manganese(III) is coordinated by two trans‐terminal and two trans‐bridging fluorine ligands, and by the O‐atoms of two briding sulphate ligands in trans position. The Jahn‐Teller effect induces a variety of antiferrodistortive ordering resulting in distorted [MnF₄O₂] octahedra with alternating elongation of F—Mn—F — and O—Mn—O — axes, respectively. Thus, only asymmetrical bridges are formed.     

ABi2(IO3)2F5 (A=K,Rb, and Cs): A Combination of Halide and Oxide Anionic Units To Create a Large Second‐Harmonic Generation Response with a Wide Bandgap

A family of nonlinear optical materials that contain the halide, oxide, and oxyhalide polar units simultaneously in a single structure, namely ABi₂(IO₃)₂F₅ (A=K ( 1 ), Rb ( 2 ), and Cs ( 3 )), have been designed and synthesized. They crystallize in the same polar space group (P 2₁) with a two‐dimensional double‐layered framework constructed by [BiF₅]²⁻ and [BiO₂F₄]⁵⁻ units connected to each other by four F atoms, in which two [IO₃]⁻ groups are linked to [BiO₂F₄]⁵⁻ unit on the same side. A hanging Bi−F bond of [BiF₅]²⁻ unit is located on the other side via ionic interaction with the layer‐inserted alkali metal ions to form three‐dimensional structure. The well‐ordered alignments of these polar units lead to a very strong second‐harmonic generation response of 12 ( 1 ), 9.5 ( 2 ), and 7.5 ( 3 ) times larger than that of potassium dihydrogen phosphate under 1064 nm laser radiation. All of them exhibited a wide energy bandgap over 3.75 eV, suggesting that they will have a high laser damage threshold.     

121,123Sb NQR investigation of chlorofluoroantimonates(III) M2SbCl3F2 (M = Rb. Cs,and NH4)

Antimony(m) chlorofluoride complexes M₂SbCl₃F₂ (M = Rb, Cs, or NH₄) were studied by the^121,123Sb NQR method. A temperature range (77–285 K) with anomalous change in the NQR parameters and a second-order phase transition at 250–280 K for (NH₄)₂SbCl₃F₂ were found.Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 382–385, February, 1996     

Einkristallstrukturbestimmungen an KBiO2 und RbBiO2 und ein kristallchemischer Vergleich der Alkalimetallbismutate(III) vom Typ MBiO2 (M = Na,K, Rb,Cs)

Single Crystal Structure Determination on KBiO₂ and RbBiO₂ and a Crystal Chemical Comparison of MBiO₂ (M = Na, K, Rb, Cs) Single crystals of KBiO₂ (colourless) and RbBiO₂ (colourless) were obtained by solid state reaction of the respective binary metal oxides. Both crystal structures (KBiO₂: C2/c; a = 783.13(9), b = 790.92(1), c = 596.86(8) pm, β = 124.81(1)°; Z = 4; 445 diffractometer data; R₁ = 0.027; wR² = 0.069; RbBiO₂: C2/c; a = 806.20(5), b = 838.88(4), c = 598.14(4) pm, β = 123.68(1)°; Z = 4; 289 diffractometer data; R₁ = 0.040; wR² = 0.101) reveal infinite [BiO₂]-chains extending along the [0 0 1] direction. The compounds are isostructural with NaBiO₂ and CsBiO₂.     

Jahn‐Teller‐Ordnung in Mangan(III)‐fluoridsulfaten. II. Phasenübergang und Verzwillingung bei K2[MnF3(SO4)] und 1D Magnetismus in Verbindungen A2[MnF3(SO4)] (A = K,NH4, Rb,Cs)

Jahn‐Teller Ordering in Manganese(III) Fluoride Sulfates. II. Phase Transition and Twinning of K₂[MnF₃(SO₄)] and 1D Magnetism in Compounds A₂[MnF₃(SO₄)] (A = K, NH₄, Rb, Cs) According to single‐crystal X‐ray investigations, K₂[MnF₃(SO₄)] crystallizes at low temperature, like the isostructural Rb, NH₄, and Cs analogues in space group P2₁/c, Z = 4, e.g. at 100 K with a = 7.197, b = 10.704, c = 8.427Å, β = 91.84°. Below about 300 K, the crystals are found to be [001] axis twins. Using a new integration method for area detector records, nearly complete intensity data could be gained allowing for structure refinements of similar quality as for untwinned crystals (e.g. at 100 K: wR₂ = 0.050, R = 0.020 for all reflections). With rising temperature, the monoclinic angle approaches continuously 90°. For an ordering parameter Δβ = β?90° a 2^nd‐order phase transition is observed with an exponent λ = 0.17. At the transition temperature of 280 K resulting from the fit, the monoclinic structure changes – with delay – to orthorhombic with the minimum super‐group Pnca, a = 7.243, b = 10.763, c = 8.457Å, R = 0.024, as found in an early structure determination at room temperature by Edwards 1971. In the chain‐like [MnF₃(SO₄)]^2? anions, manganese(III) is octahedrally coordinated by two trans‐terminal and two trans‐bridging fluorine ligands as well as by the O atoms of two trans‐bridging sulfate ligands. At low temperature, the octahedral elongation by the Jahn‐Teller effect alternates between a F–Mn–F and an O–Mn–O axis (antiferrodistortive ordering). All bridges are asymmetric. From about 320 K on they become symmetric. Due to 2D dynamical Jahn‐Teller effect all octahedra appear compressed. All compounds A₂[MnF₃(SO₄)] show 1D antiferromagnetism. The antiferrodistortive Jahn‐Teller order at low temperatures and the small bridge angles explain the much lower magnetic exchange energies and their inverse relation to the bridge angles as compared with other fluoromanganate(III) chain compounds with the usual ferrodistortive ordering.     

Rubidium-decaamidodichromat(III), Rb4Cr2(NH2)10 – Synthese und Kristallstruktur

Rubidium Decaamidodichromate(III), Rb₄Cr₂(NH₂)₁₀ – Synthesis and Crystal Structure The reaction of chromium(III) with rubidium amide in a molar ratio of Cr(NH₂)₃/RbNH₂ = 1 : 1.75 at 140 °C and p(NH₃) = 3 kbar in a high-pressure autoclave results after 90 days in dark violet crystals of Rb₄Cr₂(NH₂)₁₀. Structure determination was done by single crystal X-ray methods:Pna2₁ (No. 33), Z = 4, a = 12.244(3) Å, b = 6.727(1) Å, c = 19.775(5) Å, N(F²_o > 3σ(F²_o)) = 1046, N(Var.) = 94, R/R_w = 0,051/0,059&#TAB;The structure of Rb₄Cr₂(NH₂)₁₀ contains isolated, face-sharing N-octahedra around two Cr³⁺-ions giving [Cr(NH₂)₃(NH₂)_3/2]₂^3–. These are arranged to oneanother following the motif of a hexagonal closest packing. They are connected via Rb⁺- and one further amide ion not bound to Cr³⁺. The compound is characterized by thermoanalytical and IR-/Raman-spectroscopic measurements.     

One‐Dimensional Zinc Selenophosphates: A2ZnP2Se6 (A = K,Rb, Cs)

The new compounds A₂ZnP₂Se₆ (A = K, Rb, Cs) were synthesized via molten salt flux syntheses. The crystals feature one‐dimensional ¹/_∞[ZnP₂Se₆]^2– chains charge balanced by alkali metal ions between the chains. K₂ZnP₂Se₆ crystallizes in the monoclinic space group P2₁/c; cell parameters a = 12.537(3) Å, b = 7.2742(14) Å, c = 14.164(3) Å, β = 109.63(3)°, Z = 4, and V = 1216.7(4) ų. Rb₂ZnP₂Se₆ and Cs₂ZnP₂Se₆ are isotypic, crystallizing in the triclinic space group P$\bar{1}$ . Rb₂ZnP₂Se₆ has cell parameters of a = 7.4944(15) Å, b = 7.6013(15) Å, c = 12.729(3) Å, α = 96.57(3)°, β = 105.52(3)°, γ = 110.54(3)°, Z = 2, and V = 636.6(2) ų. Cs₂ZnP₂Se₆ has cell parameters of a = 7.6543(6) Å, b = 7.7006(6) Å, c = 12.7373(11) Å, α = 97.007(7)°, β = 104.335(7)°, γ = 109.241(6)°, Z = 2, and V = 669.54(10) ų.     

Die Akzeptoreigenschaften der Metall—Metall-Einheit in den zweikernigen Komplexen cis-M2(O2CCH3)2Cl4L2, M = Tc,Re; L = neutrale Base

The Acceptor Properties of the Metal—Metal Unit in the Dinuclear Complexes cis-M₂(O₂CCH₃)₂Cl₄L₂, M = Tc, Re; L = neutrale Base The weakly bound H₂O molecules in axial positions of the dimetalates cis-M₂(O₂CCH₃)₂Cl₄L₂, M = Tc, Re, are easily substituted on reaction with stronger donor bases. With increasing donor number D_N or donor strength D_S of the axial ligands, the metal—metal stretching frequency v₁ is lowered. The linearity between v₁ and the hard D_N scale shows, that the M₂ unit acts as a hard Lewis acid in the axial direction, according to the observation that no coordination of soft donor bases takes place. The trans influence of the metal—metal multiple bond is estimated from the ratio of the shifts observed for v₁ and the equatorial metal-ligand stretching modes after formation of adducts. The ratio is about 5: 1 in the ditechnetates and thus considerable higher than in the dirhenates with about 2: 1.     

Facile Hydrazine‐Hydrothermal Syntheses and Characterizations of Two Quaternary Thioarsenates(III): Two‐Dimensional SrAg4As2S6⋅2 H2O and One‐Dimensional BaAgAsS3

Two new quaternary thioarsenates(III), SrAg₄As₂S₆?2 H₂O ( 1 ) and BaAgAsS₃ ( 2 ), have been prepared through a hydrazine‐hydrothermal method at low temperature. Compound 1 possesses a two‐dimensional (2D) layer network, while compound 2 features a one‐dimensional (1D) column structure. The detailed structure analysis indicates that Sr²⁺ and Ba²⁺ cations have different directing effects on the structures of thioarsenates(III). Both experimental and theoretical studies demonstrate that compounds 1 and 2 are narrow‐gap semiconductors. Our success in synthesizing these two quaternary thioarsenates(III) proves that the hydrazine‐hydrothermal technique is a powerful yet facile synthetic method for exploring new complex chalcogenides with diverse crystal structures and interesting physical properties.     

Darstellung und Struktur der Tetrafluoroaurate(III) MI[AuF4] mit MI = Li,Rb

Synthesis and Structure of Tetrafluoroaurates(III) M^I[AuF₄] with M^I = Li, Rb Single crystal investigations on Rb[AuF₄], light yellow, confirm the tetragonal unit cell (K[BrF₄]-type) with a = 618.2(1) and c = 1191(1) pm, Z = 4, space group I 4/mcm-D (No. 140). Li[AuF₄], light yellow too, crystallizes monoclinic with a = 485.32(7), b = 634.29(8), c = 1004.43(13) pm, β = 92.759(12), Z = 4; space group P 2/c-C (No. 13). The structure of Li[AuF₄] is related to the Rb[AuF₄]-type of structure.     

Kristallstrukturbestimmungen an Cs2NaCr(CN)6 und weiteren Verbindungen A2BM(CN)6 (A = Rb,Cs; B = Na,K, Rb,NH4; M = Cr,Mn, Fe,Co): Oktaederkippung und Toleranzfaktor von Cyanokryolithen

Crystal Structure Determinations of Cs₂NaCr(CN)₆ and further Compounds A₂BM(CN)₆ (A = Rb, Cs; B = Na, K, Rb, NH₄; M = Cr, Mn, Fe, Co): Tilting of Octahedra and Tolerance Factor of Cyano Cryolites The crystal structures of Cs₂NaCr(CN)₆ (space group P2₁/n, Z = 2; a = 763.2(1), b = 789.8(1), c = 1102.4(1) pm, β = 90.09(1)°) and of 9 isostructural cyano cryolites A₂BM(CN)₆ of the elements M = Cr, Mn, Fe, Co were determined by X‐rays at single crystals. The results, including data from the literature, were studied with respect to the interdependence of radii resp. bond lengths and cyano bridge angles M–CN–B resp. tilting of [M(CN)₆] and [BN₆] octahedra: The average tilt angles κ of the latter are within the range 13° ≤ κ ≤ 23° and increase linearly if the modified tolerance factor t (of range 0,87 ≥ t ≥ 0,78) decreases.     

Synthese und Charakterisierung von Tetrabromoferraten(III) AFeBr4 mit einwertigen Kationen A  Cs,Rb, Tl,NH4, K,Na, Li,Ag

Preparation and Characterization of Tetrabomoferrates(III) AFeBr₄ with Monovalent Cations A ? Cs, Rb, Tl, NH₄, K, Na, Li, Ag Tetrabromoferrates(III) AFeBr₄ of the monovalent cations A ? Cs, Rb, Tl, NH₄, Na, Ag, Li have been prepared in closed ampoules by reaction of the appropriate bromides with iron and an excessive amount of bromine. The dark red compounds were characterized by DTA, Raman spectroscopy and X-ray powder diffraction. Their crystal structures have been assigned to five structure types, containing FeBr₄ anions. The coordination number runs from 12 (Cs⁺, Rb⁺) over 10 (NH₄⁺) and 8 (K⁺), to 6 (Na⁺, Ag⁺, Li⁺). Lattice parameters for all compounds see “Inhaltsübersicht”. CsFeBr₄ and RbFeBr₄ crystallize orthorhombic in the BaSO₄-type, NH₄FeBr₄ monoclinic in the KAlBr₄-type, KFeBr₄ orthorhombic in the GaGaCl₄-type, NaFeBr₄ monoclinic in the NaGaBr₄-type, AgFeBr₄ and LiFeBr₄ monoclinic in the LiAlCl₄-type, while the structure of TlFeBr₄ is still unknown.     

Ein- und zweikernige Fluorokomplexe des Titan(III), Chrom(III) und Eisen(III) Darstellung und Struktur von (NMe4)(Ti(H2O)4F2)TiF6 · H2O, (NMe4)3Cr2F9 und (NMe4)3Fe2F9

Mono- and Dinuclear Fluoro Complexes of Titanium (III), Chromium (III), and Iron(III). Syntheses and Structures of (NMe₄) (Ti(H₂O)₄F₂)TiF₆ · H₂O, (NMe₄)₃Cr₂F₉, and (NMe₄)₃Fe₂F₉ The title compounds have been prepared by reaction of MCl₃ (M = Ti, Cr, Fe) with NMe₄F in dimethylformamide. (NMe₄)₃Cr₂F₉ and (NMe₄)₃Fe₂F₉ contain the face-sharing biocathedral M₂F₉^3? unit. The M…M distances are 277.1(1) and 289.8(3) pm in (NMe₄)₃Cr₂F₉ and (NMe₄)Fe₂F₉, respectively. (NMe₄)(Ti(H₂O)₄F₂)TiF₆ · H₂O contains trans-Ti^III(H₂O)₄F₂⁺ cations and Ti^IVF₆^2? anions. Crystal data: (NMe₄)₃Cr₂F₉: hexagonal, space group P6₃/m, a = 804.1(3), c = 1857.5(4) pm, Z = 2, 529 reflections, R = 0.049; (NMe₄)₃Fe₂F₉: hexagonal, space group P6₃/m, a = 804.7(5), c = 1 861.6(5) pm, Z = 2, 635 reflections, R = 0,046; (NMe₄)(Ti(H₂O)₄F₂)TiF₆ · H₂O: orthorhombic, space group Pbca, a = 776.9(2), b = 1 616.3(3), c = 2 428.6(7) pm, Z = 8, 2 784 reflections, R = 0,056.     

Die Chlorooxoarsenate(III) (PPh4)2[As4O2Cl10] · 2 CH3CN und (PPh4)2[As2OCl6] · 3 CH3CN

The Chlorooxoarsenates(III) (PPh₄)₂[As₄O₂Cl₁₀] · 2 CH₃CN and (PPh₄)₂[As₂OCl₆] · 3 CH₃CN (PPh₄)₂[As₂Cl₈] can be prepared from As₂O₃, SOCl₂ and PPh₄Cl in acetonitrile. Its oxidation with chlorine yields PPh₄[AsCl₆]. This was also obtained directly from arsenic, chlorine and PPh₄Cl, (PPh₄)₂[As₄O₂Cl₁₀] · 2 CH₃CN being a side product; the latter was obtained with high yield from AsCl₃, As₂O₃ and PPh₄Cl in acetonitrile. By addition of PPh₄Cl it was converted to (PPh₄)₂[As₂OCl₆] · 3 CH₃CN. According to their X-ray crystal structure analyses, both crystallize in the triclinic space group P 1. The [As₄O₂Cl₁₀]^2– ion can be regarded as a centrosymmetric association product of two Cl₂AsOAsCl₂ molecules and two Cl^– ions, each Cl^– ion being coordinated with all four As atoms. In the [As₂OCl₆]^2– ion the As atoms are linked via the O atom and two Cl atoms.     

Spectrophotometry Determination of Arsenic(III) and Antimony(III) by Means of Isonicotinoylhydrazones of 4-Dimethylaminobezaldehyde (4-Dbih) and 2-Hydroxynaphthaldehyde (2-Hnih)

Abstract

4-DBIH and 2-HNIH react with As(III) and Sb(III) respectively, in CH₃COOH medium to form colored complexes stable in presence of EDTA. As(III) and Sb(III) do not react with 2-HNIH and 4-DBIH respectively, and the Sb(III)-2-HNIH complex is extractable into isoamyl alcohol. These behaviours were used for the spectrophotometry determination of As (III) and Sb(III) in presence of several cations.     

Sm2As4O9: Ein ungewöhnliches Samarium(III)‐Oxoarsenat(III) gemäß Sm4[As2O5]2[As4O8]

Sm₂As₄O₉: An Unusual Samarium(III) Oxoarsenate(III) According to Sm₄[As₂O₅]₂[As₄O₈] Pale yellow single crystals of the new samarium(III) oxoarsenate(III) with the composition Sm₄As₈O₁₈ were obtained by a typical solid‐state reaction between Sm₂O₃ and As₂O₃ using CsCl and SmCl₃ as fluxing agents. The compound crystallizes in the triclinic crystal system with the space group (No. 2, Z = 2; a = 681.12(5), b = 757.59(6), c = 953.97(8) pm, α = 96.623(7), β = 103.751(7), γ = 104.400(7)°). The crystal structure of samarium(III) oxoarsenate(III) with the formula type Sm₄[As₂O₅]₂[As₄O₈] (≡ 2 × Sm₂As₄O₉) contains two crystallographically different Sm³⁺ cations, where (Sm1)³⁺ is coordinated by eight, but (Sm2)³⁺ by nine oxygen atoms. Two different discrete oxoarsenate(III) anions are present in the crystal structure, namely [As₂O₅]^4? and [As₄O₈]^4?. The [As₂O₅]^4? anion is built up of two Ψ¹‐tetrahedra [AsO₃]^3? with a common corner, whereas the [As₄O₈]^4? anion consists of four Ψ¹‐tetrahedra with ring‐shaped vertex‐connected [AsO₃]^3? pyramids. Thus at all four crystallographically different As³⁺ cations stereochemically active non‐binding electron pairs (“lone pairs”) are observed. These “lone pairs” direct towards the center of empty channels running parallel to [010] in the overall structure, where these “empty channels” being formed by the linkage of layers with the ecliptically conformed [As₂O₅]^4? anions and the stair‐like shaped [As₄O₈]^4? rings via common oxygen atoms (O1 – O6, O8 and O9). The oxygen‐atom type O7, however, belongs only to the cyclo‐[As₄O₈]^4? unit as one of the two different corner‐sharing oxygen atoms.     

A Facile Process for the Preparation of Three‐Dimensional Hollow Zn(OH)2 Nanoflowers at Room Temperature

A facile strategy has been developed to synthesize double‐shelled Zn(OH)₂ nanoflowers (DNFs) at room temperature. The nanoflowers were generated via conversion of Cu₂O nanoparticles (NPs) using ZnCl₂ and Na₂S₂O₃ by a simple process. Outward diffusion of the Cu²⁺, produced by an oxidation process on the surface of NPs, and the inward diffusion of Zn²⁺ by coordination and migration, eventually lead to a hollow cavity in the inner NPs with a double‐shelled 3D hollow flower shapes. The thickness of the inner and outer shells is estimated to be about 20 nm, and the thickness of nanopetals is about 7 nm. The nanoflowers have large surface areas and excellent adsorption properties. As a proof of potential applications, the DNFs exhibited an excellent ability to remove organic molecules from aqueous solutions.     

Quaternary Germanides Formed in Molten Aluminum: Tb2NiAl4Ge2 and Ce2NiAl6‐xGe4‐y (x ∼ 0.24, y ∼ 1.34)

The intermetallic phases Tb₂NiAl₄Ge₂ and Ce₂NiAl_6‐xGe_4‐y (x ∼ 0.24, y ∼ 1.34) were synthesized in molten Al at temperatures below 1000 °C. Both compounds adopt the tetragonal space group I4/mmm with cell parameters of a= 4.1346(2) Å c = 19.3437(7) Å for Tb₂NiAl₄Ge₂ and a= 4.1951(9) Å and c = 26.524(7) Å for Ce₂NiAl_6‐xGe_4‐y. The Tb₂NiAl₄Ge₂ structure features NiAl₄Ge₂ layers separated by a double layer of rare earth ions. The Ce₂NiAl_6‐xGe_4‐y (x ∼ 0.24, y ∼ 1.34) structure also contains the NiAl₄Ge₂ layers along with a vacancy defect PbO‐type Al_2‐xGe_2‐y layer, and is related to the Ce₂NiGa₁₀ structure type. Ordering of vacancies cause the formation of a 3ax3b superstructure in the crystal as seen by electron diffraction experiments. Tb₂NiAl₄Ge₂ exhibits Curie‐Weiss paramagnetic behavior with an antiferromagnetic transition observed at ∼20 K. Ce₂NiAl_6‐xGe_4‐y shows a much more complex magnetic behavior possibly due to temperature induced variation in the valency of the Ce atoms.     

Synthesis,Structures, and Properties of Layered Quaternary Chalcogenides of the General Formula ALnEQ4 (A = K,Rb; Ln = Ce,Pr, Eu; E = Si,Ge; Q = S,Se)

Four related quaternary compounds containing rare‐earth metals have been synthesized employing the molten flux method and metathesis. The reactions of Eu and Rb₂S₅ with Si and Ge in evacuated fused silica ampoules at 725 °C for 150 h yielded RbEuSiS₄ ( I ) and RbEuGeS₄ ( II ), respectively. On the other hand, a reaction between CeCl₃ and K₄Ge₄Se₁₀ at 650 °C for 148 h has yielded KCeGeSe₄ ( III ) and KPrSiSe₄( IV ) was obtained by the reaction of elemental Pr, Si and Se in KCl flux at 850 °C for 168 h. Crystal data for these compounds are as follows: I , orthorhombic, space group P2₁2₁2₁ (#19), a = 6.392(1), b = 6.634(2), c = 17.001(3) Å, α = β = γ = 90°, Z = 4; II , monoclinic, space group P2₁/m (#11), a = 6.498(2), b = 6.689(3), c = 8.964(3) Å, β = 108.647(6)°, Z = 2; III , monoclinic, space group P2₁ (#4), a = 6.852(2), b = 7.025(2), c = 9.017(3) Å, β = 108.116(2)°, Z = 2; IV , monoclinic, space group P2₁ (#4), a = 6.736(2), b = 6.943(2), c = 8.990(1) Å, β = 108.262(2)°, Z = 2. The crystal structures of I ‐ IV contain two‐dimensional corrugated anionic layers of the general formula, [LnEQ₄]^? (Ln = Ce, Pr, Eu; E = Si, Ge and Q = S, Se) alternately piled upon layers of alkali cations. In addition to structural elucidation, Raman and UV‐visible spectroscopy, and magnetic measurements for compound III (KCeGeSe₄) are also discussed.