HP‐CsB5O8: Synthesis and Characterization of an Outstanding Borate Exhibiting the Simultaneous Linkage of All Structural Units of Borates

The new cesium pentaborate HP‐CsB₅O₈ is synthesized under high‐pressure/high‐temperature conditions of 6 GPa and 900 °C in a Walker‐type multianvil apparatus. The compound crystallizes in the orthorhombic space group Pnma (Z=4) with the parameters a=789.7(1), b=961.2(1), c=836.3(1) pm, V=0.6348(1) nm³, R₁=0.0359 and wR₂=0.0440 (all data). The new structure type of HP‐CsB₅O₈ exhibits the simultaneous linkage of trigonal BO₃ groups, corner‐sharing BO₄ tetrahedra, and edge‐sharing BO₄ tetrahedra including the presence of threefold‐coordinated oxygen atoms. With respect to the rich structural chemistry of borates, HP‐CsB₅O₈ is the second structure type possessing this outstanding combination of the main structural units of borates in one compound. The structure consists of corrugated chains of corner‐ and edge‐sharing BO₄ tetrahedra interconnected through BO₃ groups forming octagonal channels. Inside these channels, cesium is 13+3‐fold coordinated by oxygen atoms. ¹¹B MQMAS NMR spectra are analyzed to estimate the isotropic chemical shift values and quadrupolar parameters. IR and Raman spectra are obtained and compared to the calculated vibrational frequencies at the Γ‐point. The high‐temperature behavior is examined by means of temperature‐programmed powder diffraction.     

High‐pressure syntheses of α‐RE2B4O9 (RE = Sm,Ho), with a structure type displaying edge‐sharing BO4 tetrahedra

The compounds α‐RE₂B₄O₉, with RE = Sm (disamarium tetraborate) and Ho (diholmium tetraborate), were synthesized under conditions of high pressure and high temperature in a Walker‐type multianvil apparatus, at 7.5 GPa and 1323 K for α‐Sm₂B₄O₉ and at 10 GPa and 1323 K for α‐Ho₂B₄O₉. The crystal structures were determined from single‐crystal X‐ray diffraction data collected at room temperature. The structures are isotypic with the already known α‐RE₂B₄O₉ (RE = Eu–Dy) phases, displaying the new structural motif of edge‐sharing BO₄ tetrahedra next to the known motif of corner‐sharing BO₄ tetrahedra. As the end members of this isotypic series, the two title compounds mark the borders of the stability field of the appearance of edge‐sharing BO₄ tetrahedra.     

Das erste Vanadium(III)‐Borophosphat: Darstellung und Kristallstruktur von CsV3(H2O)2[B2P4O16(OH)4]

The First Vanadium(III) Borophosphate: Synthesis and Crystal Structure of CsV₃(H₂O)₂[B₂P₄O₁₆(OH)₄] CsV₃(H₂O)₂[B₂P₄O₁₆(OH)₄] was prepared under mild hydrothermal conditions (T = 165 °C) from mixtures of CsOH_(aq), VCl₃, H₃BO₃, and H₃PO₄ (molar ratio 1 : 1 : 1 : 2). The crystal structure was determined by X‐ray single crystal methods (monoclinic; space group C2/m, No. 12): a = 958.82(15) pm, b = 1840.8(4) pm, c = 503.49(3) pm; β = 110.675(4)°; Z = 2. The anionic partial structure contains oligomeric units [BP₂O₈(OH)₂]^5–, which are built up by a central BO₂(OH)₂ tetrahedron and two PO₄ tetrahedra sharing common corners. V^III is octahedrally coordinated by oxygen of adjacent phosphate tetrahedra and OH groups of borate tetrahedra as well as oxygen of phosphate tetrahedra and H₂O molecules, respectively (coordination octahedra VO₄(OH)₂ and VO₄(H₂O)₂). The oxidation state +3 for vanadium was confirmed by measurements of the magnetic susceptibility. The trimeric borophosphate groups are connected via vanadium centres to form layers with octahedra‐tetrahedra ring systems, which are likewise linked via V^III‐coordination octahedra. Overall, a three‐dimensional framework constructed from VO₄(OH)₂ and VO₄(H₂O)₂ octahedra as well as BO₂(OH)₂ and PO₄ tetrahedra results. The structure contains channels running along [001], which are occupied by Cs⁺ in a distorted octahedral coordination (CsO₄(H₂O)₂).     

The New High‐Pressure Sodium Tetraborate HP‐Na2B4O7

The new polymorph of sodium tetraborate HP‐Na₂B₄O₇ was synthesized under high‐pressure / high‐temperature conditions of 6 GPa and 1000 °C in a multianvil apparatus with a Walker‐type module. HP‐Na₂B₄O₇ crystallizes with nine formula units per cell in the trigonal chiral space groups P3₂21 or P3₁21. The parameters are a = 765.5(2), c = 2142.3(4) pm, V = 1.0872(3) nm³, R₁ = 0.0581, and wR₂ = 0.0809 (all data). The crystal structure of HP‐Na₂B₄O₇ is built up from interconnected “sechser” rings of alternating corner‐sharing BO₃ and BO₄ groups.     

A new polymorph of Cu3B2O6

A new polymorph of nonacopper(II) bis(orthoborate) bis(hexaoxodiborate), Cu₉(BO₃)₂(B₂O₆)₂, or Cu₃B₂O₆ with Z′ = 3, has a pseudo‐layered monoclinic structure containing BO₃ triangles and B₂O₆ units consisting of corner‐sharing BO₃ triangles and BO₄ tetrahedra. The compound was obtained during an investigation of the Li–Cu–B–O system. In contrast to the triclinic form of Cu₃B₂O₆, the layers are linked to one another by BO₄ tetrahedra.     

La4B14O27: Ein Lanthan‐ultra‐Oxoborat mit Raumnetzstruktur

La₄B₁₄O₂₇: A Lanthanum ultra‐Oxoborate with a Framework Structure Single crystals of La₄B₁₄O₂₇ could be synthesized by the reaction of La₂O₃, LaCl₃ and B₂O₃ with an access of CsCl as fluxing agent in gastightly sealed platinum ampoules within twenty days at 710 °C and appear as colourless, transparent and waterresistant platelets. The new lanthanum oxoborate La₄B₁₄O₂₇ (monoclinic, C2/c; a = 1120.84(9), b = 641.98(6), c = 2537.2(2) pm, β = 100.125(8)°; Z = 4) is built of a three‐dimensional boron‐oxygen framework containing seven crystallographically different boron atoms. Four of these B³⁺ cations are surrounded by four O^2? anions tetrahedrally, whereas the other three have only three oxygen neighbours with nearly plane triangular coordination figures. Three of the [BO₄]^5? tetrahedra form [B₃O₉]^9? rings by cyclic vertex‐condensation, which are further linked via [BO₃]^3? units to infinite layers. Two of these layers connect via one [B₂O₇]^8? unit of two corner‐shared [BO₄]^5? tetrahedra to double layers, which themselves build up a three‐dimensional framework together with chains consisting of two [BO₄]^5? tetrahedra and one [BO₃]^3? triangle. One of the two crystallographically independent La³⁺ cations (La1) is surrounded by ten O^2? anions and resides within the oxoborate double layers. (La2)³⁺ shows a (8+2)‐fold coordination of O^2? anions and occupies channels along the [110] direction.     

High‐Pressure Synthesis and Characterization of New Actinide Borates,AnB4O8 (An=Th,U)

New actinide borates ThB₄O₈ and UB₄O₈ were synthesized under high‐pressure, high‐temperature conditions (5.5 GPa/1100 °C for thorium borate, 10.5 GPa/1100 °C for the isotypic uranium borate) in a Walker‐type multianvil apparatus from their corresponding actinide oxide and boron oxide. The crystal structure was determined on basis of single‐crystal X‐ray diffraction data that were collected at room temperature. Both compounds crystallized in the monoclinic space group C2/c (Z=4). Lattice parameters for ThB₄O₈: a=1611.3(3), b=419.86(8), c=730.6(2) pm; β=114.70(3)°; V=449.0(2) ų; R₁=0.0255, wR₂=0.0653 (all data). Lattice parameters for UB₄O₈: a=1589.7(3), b=422.14(8), c=723.4(2) pm; β=114.13(3)°; V=443.1(2) ų; R₁=0.0227, wR₂=0.0372 (all data). The new AnB₄O₈ (An=Th, U) structure type is constructed from corner‐sharing BO₄ tetrahedra, which form layers in the bc plane. One of the four independent oxygen atoms is threefold‐coordinated. The actinide cations are located between the boron–oxygen layers. In addition to Raman spectroscopic investigations, DFT calculations were performed to support the assignment of the vibrational bands.     

Synthese und Kristallstruktur von Terbium(III)‐meta‐Oxoborat Tb(BO2)3 (≡ TbB3O6)

Synthesis and Crystal Structure of Terbium(III) meta‐Oxoborate Tb(BO₂)₃ (≡ TbB₃O₆) The terbium meta‐oxoborate Tb(BO₂)₃ (≡ TbB₃O₆) is obtained as single crystals by the reaction of terbium, Tb₄O₇ and TbCl₃ with an excess of B₂O₃ in gastight sealed platinum ampoules at 950 °C after three weeks. The compound appears to be air‐ and water‐resistant and crystallizes as long, thin, colourless needles which tend to growth‐twinning due to their marked fibrous habit. The crystal structure of Tb(BO₂)₃ (orthorhombic, Pnma; a = 1598.97(9), b = 741.39(4), c = 1229.58(7) pm; Z = 16) contains strongly corrugated oxoborate layers {(BO₂)^‐} built of vertex‐linked [BO₄]^5‐ tetrahedra (d(B‐O) = 143 ‐ 154 pm, ?(O‐B‐O) = 102‐115°) which spread out parallel (100). The four crystallographically different Tb³⁺ cations all exhibit coordination numbers of eight towards the oxygen atoms (d(Tb‐O) = 228‐287 pm). The corresponding metal cation polyhedra [TbO₈]¹³⁺ too convene to layers (composition: {(Tb₂O₁₁)^16‐}) which are likewise oriented parallel to the (100) plane.     

[O2Pb3]2(BO3)Br: An Oxidoborate Oxide Bromide with the ∞1[O2Pb3] Double Chains Based on Edge‐sharing OPb4 Tetrahedra

Through extensive research on the PbO / PbBr₂ / B₂O₃ system, a new single crystal of yellow lead‐containing oxyborate bromine, [O₂Pb₃]₂(BO₃)Br, was grown from the melt. It crystallizes in the centrosymmetric space group Cmcm (no. 63) of the orthorhombic system with the following unit cell dimensions: a = 9.5748(8) Å, b = 20.841(2) Å, c = 5.7696(5) Å, and Z = 4. The whole structure is characterized by an infinite one‐dimensional (1D) _∞¹[O₂Pb₃] double chain, which is based on the OPb₄ oxocentered tetrahedra and considered as the derivative of the continuous sheet of OPb₄ tetrahedra from the tetragonal modification of α‐PbO. The 1D _∞¹[O₂Pb₃] double chains are further bridged by the BO₃ units through common oxygen atoms to form two‐dimensional (2D) _∞¹[[(O₂Pb₃)(BO₃)] layers, with Br atoms situated between the layers. IR spectroscopy, UV/Vis/NIR diffuse reflectance spectroscopy, and thermal analysis were also performed on the reported material.     

(Ni3–xMgx)[B3P3O12(OH)6] · 6 H2O (x ≈ 1.5): A Novel BorophosphateHydrate Containing Isolated Six‐Membered Rings of Tetrahedra

A novel borophosphate‐hydrate, (Ni_3–xMg_x)[B₃P₃O₁₂(OH)₆] · 6 H₂O (x ≈ 1.5), has been prepared by hydrothermal synthesis (T = 170 °C) from a mixture of NiCl₂ · 6 H₂O, Mg(OH)₂, B₂O₃ and H₃PO₄. The crystal structure was determined at 293 K from single‐crystal X‐ray diffraction data (trigonal, R3c (no. 167), a = 14.957(10) Å, c = 13.812(6) Å, V = 2676(2) ų, Z = 6, R₁ = 0.0276, wR₂ = 0.0714 for 779 observed reflections with I > 2σ(I)). The crystal structure contains unbranched six‐membered rings [B₃P₃O₁₂(OH)₆]^6– of alternating corner linked borate and phosphate tetrahedra, which are stacked along [001] and connected via M^IIO₂(OH)₂(H₂O)₂ coordination polyhedra. Hydrogen bonding between the tetrahedral six‐membered rings and M^IIO₂(OH)₂(H₂O)₂ octahedra leads to a further cross‐linking. With respect to the arrangement of isolated six‐membered tetrahedral rings the crystal structure of this borophosphate‐hydrate is closely related to the cyclo‐hexasilicate dioptase, Cu₆[Si₆O₁₈] · 6 H₂O.     

High‐Pressure Synthesis and Single‐Crystal Structure Elucidation of the Indium Oxide‐Borate In4O2B2O7

The indium oxide‐borate In₄O₂B₂O₇ was synthesized under high‐pressure/high‐temperature conditions at 12.5 GPa/1420 K using a Walker‐type multianvil apparatus. Single‐crystal X‐ray structure elucidation showed edge‐sharing OIn₄ tetrahedra and B₂O₇ units building up the oxide‐borate. It crystallizes with Z = 8 in the monoclinic space group P2₁/n (no. 14) with a = 1016.54(3), b = 964.55(3), c = 1382.66(4) pm, and β = 109.7(1)°. The compound was also characterized by powder X‐ray diffraction and vibrational spectroscopy.     

Syntheses of Halogenated Polyhedral Phosphaboranes: Crystal Structure of conjuncto‐3,3′‐(closo‐1,2‐P2B4Br3)2

Co‐pyrolysis of B₂Br₄ with PBr₃ at 480 °C gave, in addition to the main product closo‐1,2‐P₂B₄Br₄, conjuncto‐3,3′‐(1,2‐P₂B₄Br₃)₂ ( 1 ) and the twelve‐vertex closo‐1,7‐P₂B₁₀Br₁₀ ( 2 ), both in low yields. X‐ray structure determination for 1 [triclinic, space‐group P1 with a = 7.220(2) Å, b = 7.232(2) Å, c = 8.5839(15) Å, α = 97.213(15)°, β = 96.81(2)°, γ = 94.07(2)° and Z = 1] confirmed that 1 adopts a structure consisting of two symmetrically boron–boron linked distorted octahedra with the bridging boron atoms in the 3,3′‐positions and the phosphorus atoms in the 1,2‐positions. The intercluster 2e/2c B–B bond length is 1.61(3) Å. The shortest boron–boron bond within the cluster framework is 1.68(2) Å located between the boron atoms antipodal to the phosphorus atoms. The icosahedral phosphaborane 2 was characterized by ¹¹B‐¹¹B COSY NMR spectroscopy showing cross peaks indicative for the isomer with the phosphorus atoms in 1,7‐positions. Both the X‐ray data of 1 and the NMR spectroscopic data of 1 and 2 give further evidence for the influence of an antipodal effect of heteroatoms to cross‐cage boron atoms and, vice versa, of an additional shielding of the phosphorus atoms caused by B‐Hal substitution at the boron positions trans to phosphorus.     

Mixed Alkali Neodymium Orthoborates: K9Li3Nd3(BO3)7 and A2LiNd(BO3)2 (A = Rb,Cs)

Crystals of mixed alkali neodymium orthoborates, K₉Li₃Nd₃(BO₃)₇ and A₂LiNd(BO₃)₂ (A = Rb, Cs) were obtained by spontaneous crystallization. K₉Li₃Nd₃(BO₃)₇ crystallizes in space group P2/c with cell parameters of a = 11.4524(7) Å, b = 10.1266(6) Å, c = 12.3116 (10) Å, β = 122.0090(10)°. In the structure, NdO₈ polyhedra share corners and connect with planer BO₃ groups to form infinite [Nd₃B₃O₂₁]_n chains. These chains are linked by additional BO₃ groups to produce a double layer of [Nd₆B₆O₃₈]_n blocks in the ac plane with K and Li ions filled into the cavities. A₂LiNd(BO₃)₂ (A = Rb, Cs) crystallizes in space group Pbcm, with cell parameters of a = 7.113(2) Å, b = 9.691(3) Å and c = 10.135(3) Å for Rb₂LiNd(BO₃)₂, and a = 7.2113(3) Å, b = 9.9621(4) Å, and c = 10.3347(4) Å for Cs₂LiNd(BO₃)₂. In the structure, NdO₈ polyhedra are corner‐sharing with each other and further interlinked by BO₃ groups to comprise the infinite [Nd₄B₄O₂₄] sheets in the bc plane, with Rb/Cs and Li ions occupying the interlayered space. The compounds show effective near‐IR emission and their associated lifetimes are obtained by fluorescence spectra.     

A New Sodium Borate: Na[B6O8(OH)3]·6H2O·H3BO3

The structure of [B₆H₉NaO₁₄, H₃BO₃, 6H₂O] was determined by single‐crystal X‐ray diffraction and further analyzed by FTIR spectroscopy and differential thermal/thermogravimetric analysis. The asymmetric unit contains Na–O polyhedra (distorted octahedron), [B₆O₈(OH)₃]^– fundamental building blocks, one free water molecule and one free H₃BO₃ molecule. In the hexaborate anion, three B₃O₃ rings are linked by a common oxygen atom with five trigonal and one tetrahedral boron atoms. The hexaborate group is also linked to the oxygenated environment of the sodium atom by three other six‐membered rings, each of which involve two boron atoms, three oxygen atoms, and sodium as the joint atom.     

Cd3[B2P4O14(OH)4]: A 3D Open‐Framework Cadmium Borophosphate with Unique Twisted 8‐Ring Channels

Abstract. The cadmium borophosphate compound Cd₃[B₂P₄O₁₄(OH)₄] was synthesized under mild hydrothermal conditions. The crystal structure was determined by single‐crystal X‐ray diffraction [triclinic, space group P$\bar{1}$ (no. 2), a = 5.4362(11) Å, b = 8.2190(16) Å, c = 8.3918(17) Å, and α = 111.87(3)°, β = 104.63(3)°, γ = 90.73(3)°, V = 334.29(12) ų and Z = 1]. The 3D open framework of the title compound is constructed from BO₃(OH) tetrahedra and 2D layers along the [100] direction. The resulting framework contains twisted eight‐membered rings that form 1D channels.     

Synthetic,Structural, and Spectroscopic Investigations of K3Nb8O21‐type Complex Oxides K3MTa7O21 (M = Ti,Zr)

Potassium‐containing zirconium(IV)/titanium(IV) tantalum(V) oxides, K₃TiTa₇O₂₁ ( 1 ) and K₃ZrTa₇O₂₁ ( 2 ), of K₃Nb₈O₂₁‐type of compounds are afforded from potassium‐molybdate flux. Both compounds crystallize in the hexagonal space group P6₃/mcm (no. 193) with a = 908.69(2), c = 1202.83(7) pm and c/a = 1.324 (Z = 2) for 1 and a = 913.30(3), c = 1219.21(6) pm and c/a = 1.335 (Z = 2) for 2 , respectively. The Structural motif of [MTa₇O₂₁]^3– (M = Ti⁴⁺ or Zr⁴⁺) consists of edge‐shared (M,Ta)₆O₂₄‐units that are similar to corner‐sharing Ta₆O₂₇ units of synthetic soro‐silicate K₃Ta₃Si₂O₁₃ and double borate K₃Ta₃B₂O₁₂. The solid state bandgap measurements revealed that calculated values (3.26 eV for K₃TiTa₇O₂₁ and 3.14 eV for K₃ZrTa₇O₂₁) are dependent on aperture of Ta–O–Ta bond angle as it was previously shown for perovskite‐type tantalate photocatalysts.     

Die Oxoantimonate(III) Rb2Sb8O13 und Cs8Sb22O37: Neue Schicht‐ und Gerüststrukturen mit ‘Lone‐Pair’ ‐Kationen

The Oxoantimonates(III) Rb₂Sb₈O₁₃ and Cs₈Sb₂₂O₃₇: New Framework and Layer Structures with ‘Lone‐Pair’ Cations The oxoantimonates(III) Rb₂Sb₈O₁₃ and Cs₈Sb₂₂O₃₇ were synthezised from Sb₂O₃, the elemental alkali metals (A) and the hyperoxides (AO₂) at 500 °C. The crystal structures of Rb₂Sb₈O₁₃ (monoclinic, P2₁/m, a=743.7(12)pm, b=1724(3)pm, c=1380(2)pm, β=90.44(4) °, Z=4) and Cs₈Sb₂₂O₃₇ (monoclinic, Cc, a=1299.93(11)pm, b=719.87(6)pm, c=3089.9(3)pm, β=96.00(2) °, Z=2) exhibit complex layer (Rb) and framework oxoantimonate ions (Cs), with the Sb^III cation, due to its stereochemically active ‘lone‐pair’, in ψ‐tetrahedral (CN=3) to ψ‐trigonal‐bipyramidal (CN=4) coordination by O.     

Synthesis,Spectroscopic, and X‐Ray Diffraction Studies of cis‐Dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl3 H‐pyrazol‐3‐onato) Tin(IV)

Reaction between an aqueous ethanol solution of tin(II) chloride and that of 4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐one in the presence of O₂ gave the compound cis‐dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐onato) tin(IV) [(C₂₆H₂₆N₄O₄)SnCl₂]. The compound has a six‐coordinated Sn^IV centre in a distorted octahedral configuration with two chloro ligands in cis position. The tin atom is also at a pseudo two‐fold axis of inversion for both the ligand anions and the two cis‐chloro ligands. The orange compound crystallizes in the triclinic space group P 1 with unit cell dimensions, a = 8.741(3) Å, b = 12.325(7) Å, c = 13.922(7) Å; α = 71.59(4), β = 79.39(3), γ = 75.18(4); Z = 2 and D_x = 1.575 g cm^–3. The important bond distances in the chelate ring are Sn–O [2.041 to 2.103 Å], Sn–Cl [2.347 to 2.351 Å], C–O [1.261 to 1.289 Å] and C–C [1.401 Å] the bond angles are O–Sn–O 82.6 to 87.7° and Cl–Sn–Cl 97.59°. The UV, IR, ¹H NMR and ¹¹⁹Sn Mössbauer spectral data of the compound are reported and discussed.     

Complex Topology of Uranyl Polyphosphate Frameworks: Crystal Structures of α‐, β‐K[(UO2)(P3O9)] and K[(UO2)2(P3O10)]

Three new uranyl polyphosphates, α‐K[(UO₂)(P₃O₉)] ( 1 ), β‐K[(UO₂)(P₃O₉)] ( 2 ), and K[(UO₂)₂(P₃O₁₀)] ( 3 ), were prepared by high‐temperature solid‐state reactions. The crystal structures of the compounds have been solved by direct methods: 1 – monoclinic, P2₁/m, a = 8.497(1), b = 15.1150(1), c = 14.7890(1) Å, β = 91.911(5)°, V = 1898.3(3) ų, Z = 4, R₁ = 0.0734 for 4181 unique reflections with |F₀| ≥ 4σ_F; 2 – monoclinic, P2₁/n, a = 8.607(1), b = 14.842(2), c = 14.951(1) Å, β = 95.829(5)°, V = 1900.0(4) ų, Z = 4, R₁ = 0.0787 for 3185 unique reflections with |F₀| ≥ 4σ_F; 3 – Pbcn, a = 10.632(1), b = 10.325(1), c = 11.209(1) Å, V = 1230.5(2) ų, Z = 4, R₁ = 0.0364 for 1338 unique reflections with |F₀| ≥ 4σ_F. In the structures of 1 and 2 , phosphate tetrahedra share corners to form infinite [PO₃]^? chains, whereas, in the structure of 3 , tetrahedra form linear [P₃O₁₀]^5? trimers. The structures are based upon 3‐D frameworks of U and P polyhedra linked by sharing common O corners. The infinite [PO₃]^? chains in the structures of 1 and 2 are parallel to [100] and [–101], respectively. The uranyl polyphosphate frameworks are occupied by host K⁺ cations.     

3Mg(OH)2·MgSO4·8H2O: A Metastable Phase in the System Mg(OH)2‐MgSO4‐H2O

In the course of investigations relating to magnesia oxysulfate cement the basic magnesium salt hydrate 3Mg(OH)₂ · MgSO₄ · 8H₂O (3–1–8 phase) was found as a metastable phase in the system Mg(OH)₂‐MgSO₄‐H₂O at room temperature (the 5–1–2 phase is the stable phase) and was characterized by thermal analysis, Raman spectroscopy, and X‐ray powder diffraction. The complex crystal structure of the 3–1–8 phase was determined from high resolution laboratory X‐ray powder diffraction data [space group C2/c, Z = 4, a = 7.8956(1) Å, b = 9.8302(2) Å, c = 20.1769(2) Å, β = 96.2147(16)°, and V = 1556.84(4) ų]. In the crystal structure of the 3–1–8 phase, parallel double chains of edge‐linked distorted Mg(OH₂)₂(OH)₄ octahedra run along [–110] and [110] direction forming a pattern of crossed rods. Isolated SO₄ tetrahedra and interstitial water molecules separate the stacks of parallel double chains.