High-pressure Synthesis,Structure, IR Spectroscopy,and Theoretical Calculations of the New Silver Tetraborate Ag2B4O7 with a Unique Crystal Structure

Ag₂B₄O₇ is synthesized at high-pressure/high-temperature conditions of 11 GPa and 1073 K in a multianvil device. It crystallizes in the monoclinic centrosymmetric space group P2₁/c (no. 14) with four formula units per unit cell (Z=4). The cell parameters are a=787.53(3), b=651.63(2), c=943.88(3) pm, β=107.911(2)°, and V=460.90(3) ų. Ag₂B₄O₇ crystallizes in a unique crystal structure that consists of complex anionic borate layers with Ag⁺ ions in between. Additionally, the silver cations show argentophilic interactions. The compound was analysed via single-crystal and powder diffraction as well as infrared spectroscopy. Furthermore, theoretical calculations at HSEsol level were conducted.     

Synthesis,Crystal Structure and Vibrational Spectroscopy of NH4[Co(NH3)5(H2O)][B4O5(OH)4]2·6H2O

A novel hydrated cobalt tetraborate complex NH₄[Co(NH₃)₅(H₂O)][B₄O₅(OH)₄]₂·6H₂O, was synthesized by the reaction of NH₄‐borate aqueous with CoCl₂ and its structure was determined by single crystal X‐ray diffraction. The crystal system of this complex is orthorhombic, the space group is Pnma, and the unit cell parameters are a=1.2901(2) nm, b=1.6817(3) nm, c=1.1368(2) nm, α=β=γ=90°, V=2.4742(8) nm³, and Z=4. This compound contains infinite borate layers constructed from [B₄O₅(OH)₄]^2? units via hydrogen bonds. The adjacent polyborate anion layers are further linked together with the octahedral [Co(NH₃)₅(H₂O)]³⁺ groups through hydrogen bonds to form 3D framework. The groups and guest water molecules are deposited in the empty space of this framework and interact with the layers by extensive hydrogen bonds. Infrared and Raman spectra (4000–400 cm^?1) of NH₄[Co(NH₃)₅(H₂O)][B₄O₅(OH)₄]₂·6H₂O were recorded at room temperature and analyzed. Fundamental vibrational modes were identified and band assignments were made. The middle band observed at 575 cm^?1 in Raman spectrum is the pulse vibration of [B₄O₅(OH)₄]^2?.     

Synthesis and crystal structure of the high-pressure iron borate α-FeB2O4

The high-pressure iron borate α-FeB₂O₄ was synthesized under high-pressure and high-temperature conditions in a Walker-type multianvil apparatus at 7.5 GPa and 1100 °C. The monoclinic iron borate crystallizes with eight formula units in the space group P2₁/c with the lattice parameters a=715.2(2), b=744.5(2), c=862.3(2) pm, and β=94.71(3)°. The compound is built up exclusively from corner-sharing BO₄-tetrahedra, isotypic to the monoclinic phases β-SrGa₂O₄, CaAl₂O₄-II, and CaGa₂O₄. Additionally, the structure is closely related to the orthorhombic compound BaFe₂O₄. The structure consists of layers of six-membered rings, which are interconnected to a three-dimensional network. The iron cations are coordinated by six and seven oxygen atoms. Next to synthesis and crystal structure of the new high-pressure borate, structural coherences to other structure types are discussed.     

Low Temperature Flux Synthesis and Characterizations of a New Layered Barium Borate BaB8O11(OH)4

The new hydroxyl barium borate BaB₈O₁₁(OH)₄ was synthesized by using a low‐temperature molten salt technique with boric acid as flux at 458 K. Its crystal structure was determined from single‐crystal X‐ray data. The compound crystallizes in the monoclinic space group P12₁/n1 (No.14) with unit cell of a = 790.80(16) pm, b = 1393.9(3) pm, c = 1004.7(2) pm, β = 90.00(3)°, V = 1107.6(4) × 10⁶ pm³, Z = 2. It is isostructural to PbB₈O₁₁(OH)₄, but obviously different from AB₈O₁₁(OH)₄ (A = Ca, Sr) in cell. The crystal structure of BaB₈O₁₁(OH)₄ is built from corrugated borate layers,{[B₈O₁₁(OH)₄]^2–}_n parallel to (010), which are stacked along the b axis and are linked by barium atoms. The borate layer consists of [B₆O₉(OH)] clusters as fundamental building blocks (FBBs), which are connected with surrounding four FBBs by sharing common oxygen vertices to form a sheet, and the sheet is further decorated with the flanking [B₂O₂(OH)₃] dimers. FT‐IR and Raman spectroscopy, DTA‐TG, and the identification of an intermediate phase are presented.     

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 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.     

Synthesis and crystal structure of strontium borate Sr<Subscript>4</Subscript>B<Subscript>14</Subscript>O<Subscript>25</Subscript>

The new compound Sr₄B₁₄O₂₅ (4SrO · 7B₂O₃) corresponding to an oxide ratio of 4: 7 has been identified and synthesized in the SrO-B₂O₃ system. The crystal structure of the compound has been determined (space group Cmc2₁, a = 7.734(5) Å, b = 16.332(5) Å, c = 14.556(5) Å, Z = 4, 702 F(hkl), R = 0.078). The borate anions form a three-dimensional framework consisting of borate groups of two types: three-ring structures (2□, Δ) and BO₃ triangles. Layers formed by 14-membered rings composed of boron-oxygen tetrahedra and triangles packed within the layer according to the herringbone pattern can be distinguished in the framework. The strontium atoms are located on the mirror symmetry planes between these layers. The compound is metastable and decomposes, on long-term storage, into strontium di- and metaborate.     

La2XB3 (X = Cl,Br): A Novel Layered Structure with Planar Boron Nets of B3, B6 and B8 Rings

Two new layered rare earth boride halides, La₂XB₃ (X = Cl, Br) have been synthesized. They crystallize in the space group (No. 174) with a = 7.872(1) Å, c = 8.219(2) Å, V = 441.1(1) ų for the chloride, and with a = 7.834(1) Å, c = 8.440(1) Å, V = 448.6(1) ų for the bromide compound, respectively. The crystals of La₂ClB₃ are twinned resulting in an apparent symmetry P6/mmm (No. 191). In the crystal structure of La₂XB₃, trigonal La₆ prisms are condensed into sheets in the a‐b plane, and the halogen atoms X sandwich the La double layers. The connection of B atoms which center the prisms and rectangular prism faces leads to B nets of B₃, B₆ and B₈ rings embedded between the La atom double layers. The chemical bonding is analyzed for the well ordered bromide, and the characteristic disorder in the chloride is discussed.     

Synthesis and Crystal Structure of the Zinc Borate Zn3B4O9

The new zinc borate Zn₃B₄O₉ was synthesized at high-pressure/high-temperature conditions of 10 GPa and 1173 K in a Walker-type multianvil pressure device. It crystallizes in the space group P (no. 2) with a=5.5028(2) Å, b=6.7150(3) Å, c=7.8887(3) Å, α=83.99(1)°, β=73.38(1)°, γ=74.75(1)°, V=269.35(2) ų, and two formula units (Z=2) per unit cell. The structure was confirmed via single-crystal X-ray diffraction. Zn₃B₄O₉ can be synthesized phase pure, which is shown with a Rietveld refinement. IR-spectroscopic data of a powder sample were collected.     

Halogenide der Seltenerdmetalle Ln4X5Z. Teil 3: Das Chlorid La4Cl5B4 – Präparation,Struktur und Verwandtschaft zu La4Br5B4, La4I5B4

Rare Earth Halides Ln₄X₅Z. Part 3: The Chloride La₄Cl₅B₄ – Preparation, Structure, and Relation to La₄Br₅B₄, La₄I₅B₄ La₄Cl₅B₄ is synthesized by reaction of LaCl₃, La metal and boron in sealed Ta containers at 1050 °C < T < 1350 °C. It crystallizes in the monoclinic space group C2/m with a = 16.484(3) Å, b = 4.263(1) Å, c = 9.276(2) Å and β = 120.06(3)°. Ce₄Cl₅B₄ is isotypic, a = 16.391(3) Å, b = 4.251(1) Å, c = 9.180(2) Å and β = 120.20(3)°. The La atoms form strings of trans-edge shared La octahedra, and the B atoms inside the strings form B₄-rhomboids, which are condensed to chains via opposite corners. The Cl atoms interconnect the channels according to La₂La_4/2Clⁱ⁻ⁱ_6/2Cl^i−a_2/2Cl^a−i_2/2. The crystal structures of the bromide and the iodide are comparabel, however, the interconnection of the strings is different in the three structure types, as 14 Cl, 13 Br and 12 I atoms surround the La₆ octahedra.     

Pr3Mo4B6O24(OH)3: High-Pressure/High-Temperature Synthesis of an Acentric Rare Earth Molybdenum Borate

We report on the synthesis of a new praseodymium molybdenum borate under high-pressure/high-temperature conditions. The new compound with the sum formula Pr₃Mo₄B₆O₂₄(OH)₃ crystallizes acentrically in the monoclinic space group Cm displaying a new structure type. The structure was solved via single-crystal structure determination. Additionally, the proposed structural model was confirmed by powder X-ray diffraction, second harmonic generation measurement, and single-crystal infrared and Raman spectroscopic investigation.     

Na6B13O22.5, a new noncentrosymmetric sodium borate

Na₆B₁₃O_22.5 (B/Na=2.17) single crystals were obtained by heating, melting and appropriately cooling borax, Na₂[B₄O₅(OH)₄]·8H₂O. Its formula has been determined by the resolution of the structure from single-crystal X-ray diffraction data. The compound crystallizes in the noncentrosymmetric orthorhombic Iba2 space group, with the following unit cell parameters: a=33.359(11) Å, b=9.554(3) Å, c=10.644(4) Å; V=3392.4(19) Å³; Z=8. The crystal structure was solved from 3226 reflections until R₁=0.0385. It exhibits a three-dimensional framework built up from BO₃ triangles (Δ) and BO₄ tetrahedra (T). Two kinds of borate groups can be considered forming two different double B₃O₃ rings: two B₄O₉ (linkage by two boron atoms) and one B₅O₁₁ (linkage by one boron atom); the shorthand notation of the new fundamental building block (FBB) existing in this compound is: 13: ∞³ [(5: 3Δ+2T)+2(4: 2Δ+2T)]. The discovery of this new borate questions the real number of Na₂B₄O₇ varieties. The existence of Na₆B₁₃O_22.5 (B/Na=2.17) and of another recently discovered borate, Na₃B₇O₁₂ (B/Na=2.33; FBB 7: ∞³ [(3: 2Δ+T)+(3: Δ+2T)+(1: Δ)], with a composition close to the long-known borate α-Na₂B₄O₇ (B/Na=2; FBB 8: ∞³ [(5: 3Δ+2T)+(3: 2Δ+T)], may explain the very complex equilibria reported in the Na₂O-B₂O₃ phase diagram, especially in this range of composition.     

Compounds and phase compatibilities in the system La2O3---SrO---CuO at 950°C

The subsolidus phase diagram of the system La₂O₃---SrO---CuO at 950°C under 1 bar of pure oxygen has been investigated and a new ternary compound, La_1+xSr_2−xCu₂O_5.5+δ with 0.05 ≤ x ≤ 0.15, was isolated. This compound crystallizes in an orthorhombic unit cell with lattice constants related to the lattice constant of the perovskite cubic unit cell, a_p, by a = 3.80 Å a_p, B = 11.48 Å 3a_p, and c = 20.23 Å 5a_p. The structure is isotypical to that of LnSr₂Cu₂O_5.5+δ with Ln = Sm, Eu, or Gd. Reported data on the crystal chemistry of the equilibrium compounds in the system La₂O₃---SrO---CuO have been summarized and compared with the present data. The structure of all compounds is built up of a La---O rock-salt layer separated by a number of LaCuO₃ perovskite layers. The general formula is (La---O)(LaCuO₃)_n where La can be replaced either partly or completely by Sr. Compounds are found for n = 1, 2, and ∞. The structures of the compounds show different types of oxygen vacancy ordering.     

Synthesis,Crystal Structure,Vibrational Spectroscopy and Thermal Behavior of the First Alkali Metal Hydrated Hexaborate： K2[B6O9（OH）2]

New hydrated potassium hexaborate K2[B6O9（OH）2] has been synthesized under mild solvothermal conditions. The structure was determined by single-crystal X-ray diffraction and further characterized by FT-IR, Rarnan spectra and DTA-TG. It crystallizes in the monoclinic system with space group P21/n, a=0.9036（2） nm, b=0.66052（18） nm, c=1.5997（4） nm, β=91.862（4）°, V=0.9543（4） nm^3 and Z=4. Its crystal structure consists of K-O polyhedra and 1-D stepped polyborate chains constructed by new [B6O9（OH）2]2- fundamental building blocks. 1-D polyborate chains contain 3,8-membered boron rings. Adjacent chains are further linked via H-bonding interactions into 2-D layers. The K^＋ cations reside not only between the layers but also in the 8-membered boron rings of the chains, compensating the negative charges of the borate chains and holding the layers together into the 3-D structure through bonding with oxygen atoms of the chains.     

Synthesis,Crystal Structure,and Properties of a New Lead Aluminum Fluoride Borate,Pb6AlB2O7F7

A new compound, Pb₆AlB₂O₇F₇, was synthesized from the PbF₂/B₂O₃ flux system, which is the first compound found in the PbF₂/Al₂O₃/B₂O₃ system. It crystallizes in the orthorhombic system, space group Cmca (No. 64) with unit cell parameters a = 11.649(7) Å, b = 18.300(11) Å, c = 6.394(4) Å, Z = 4. The crystal structure of Pb₆AlB₂O₇F₇ contains the group [Pb₆BO₁₁F₁₀] as basal building unit, which connects with each other forming two‐dimensional _∞[Pb₆BO₁₁F₁₀] layers, whereas aluminum atoms are filled in the interlayers. The IR spectrum further confirms the presence of BO₃ groups. The calculated band structures and the density of states of Pb₆AlB₂O₇F₇ suggest that its indirect gap is 2.968 eV. The DSC analysis and X‐ray diffraction technique prove that Pb₆AlB₂O₇F₇ is a congruent‐melting compound.     

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.     

[NH3CH2CHCH3NH3]][B8O11(OH)4]·H2O: Synthesis and characterization of the first 1D borate templated by 1,2-diaminopropane

A new hydrated borate compound, [NH₃CH₂CHCH₃NH₃]][B₈O₁₁(OH)₄]·H₂O 1, has been synthesized in the presence of 1,2-diaminopropane acting as a structure-directing agent under mild conditions. Its structure was determined by single crystal X-ray diffraction and further characterized FTIR, elemental analysis, powder X-ray diffraction and thermogravimetric analysis. Compound 1 crystallizes in the monoclinic system, space group P2₁/c (No. 14), a=10.0787(7) Å, b=8.8482(6) Å, c=19.3097(4) Å, β=91.352(6)°, V=1721.53(2) Å³, and Z=4. The structure consists of infinite open-branched borate chains constructed from [B₃O₆(OH)] units, onto which the [B₅O₇(OH)₃] groups are grafted. It represents the first example of one-dimensional borate templated by an organic amine. The adjacent borate chains are further linked together by extensive hydrogen bonds to form a 3D supramolecular network. The diprotonated organic amines and guest water molecules are filled in the free space of the hydrogen-bonded network and interact with the inorganic framework by extensive hydrogen bonds.     

Synthesis and Crystal Structure of Commensurate Polymorph of Ln4AlCu2B9O23 (Ln=Lu,Ho) and Refinement of Cu2Al6B4O17

Single crystals of new Cu,Lu(Ho)–alumoborate and known Cu,Al–borate were synthesized through reaction between CuB₂O₄ and LnBO₃ on the Al₂O₃ surface by annealing at 1100 °C. Structure of commensurate modification of Ln₄AlCu₂B₉O₂₃, (Ln = Lu,Ho), sp. gr. , was solved at room temperature. It was found that a low–temperature (110 K) modification possesses incommensurate modulations with modulation vector q =(0, 0, 0.132). The nonaborate block – [B₉O₂₃]^19– – 9[6T+3Δ] forms an isolated unique dense closed anionic unit. This block is terminated by Al–tetrahedrons in the chessboard pattern, resulting in formation of complex alumoborate layer [AlB₉O₂₃]^16–. Apical oxygen of central BO₃ triangle of the nonaborate block seems to be the source of modulations observed in low temperature polymorph. Cationic layers with the Ln and Cu atoms are alternating along c axis with anionic layers. The structure Cu₂Al₆B₄O₁₇, previously studied by the Rietveld method, was corroborated by single crystal data and was compared with LiAl₇B₄O₁₇.     

The first silver bismuth borate,AgBi2B5O11

The first silver bismuth borate, AgBi₂B₅O₁₁ (silver dibismuth pentaborate), has been prepared via glass crystallization in the Ag₂O–Bi₂O₃–B₂O₃ system and characterized by single‐crystal X‐ray diffraction. Its structure is derived from that of centrosymmetric Bi₃B₅O₁₂ by ordered substitution of one Bi³⁺ ion for Ag⁺, which results in the disappearance of the mirror plane and inversion centre. Second harmonic generation (SHG) measurements confirm the acentric crystal structure. It is formed by [Bi₂B₅O₁₁]_∞ layers stretched along c and comprised of vertex‐sharing B₅O₁₀ and BiO₃ groups which incorporate the Ag⁺ cations. The new compound was characterized by thermal analysis, high‐temperature powder X‐ray diffraction, and vibrational and UV–Vis–NIR (near infrared) spectroscopy. Its thermal expansion is strongly anisotropic due to the presence of rigid B₅O₁₀ groups aligned in a parallel manner. The minimal value is observed along their axis [parallel to c, α_c = 3.1 (1) × 10^?6 K^?1], while maximal values are observed in the ab plane [α_a = 20.4 (2) and α_b = 7.8 (2) × 10^?6 K^?1]. Upon heating, AgBi₂B₅O₁₁ starts to decay above 684 K due to partial reduction of silver; incongruent melting is observed at 861 K. According to density functional theory (DFT) band‐structure calculations, the new compound is a semiconductor with an indirect energy gap of 3.57 eV, which agrees with the experimental data (absorption onset at 380 nm).     

Synthesis,Structure and Thermodynamic Property of a New Lithium Borate: Li4[B8O13(OH)2]·3H2O

A new hydrated lithium borate, Li₄[B₈O₁₃(OH)₂]·3H₂O, has been hydrothermally synthesized and characterized by single crystal X‐ray diffraction, FT‐IR spectroscopy, simultaneous TGA‐DTA and chemical analysis. It crystallizes in the triclinic, space group , a=8.4578(5) Å, b=8.7877(5) Å, c=10.8058(7) Å, α=87.740(3)°, β=71.819(3)°, γ=61.569(3)°, Z=2, V=665.26(7) ų, D_c=2.043 g/cm³. Its crystal structure features polyborate anionic layers with the larger odd 13‐membered boron rings constructed by [B₈O₁₃(OH)₂]^4? FBBs. Through designing the thermochemical cycle, the standard molar enthalpy of formation of this borate was determined to be ?(7953.8±6.6) kJ·mol^?1 by using a heat conduction microcalorimeter.