Oxonium Ions Substituting Cesium Ions in the Structure of the New High‐Pressure Borate HP‐Cs1−x(H3O)xB3O5 (x=0.5–0.7)

The new high‐pressure borate HP‐Cs_1?x(H₃O)_xB₃O₅ (x=0.5–0.7) was synthesized under high‐pressure/high‐temperature conditions of 6 GPa/900 °C in a Walker‐type multianvil apparatus. The compound crystallizes in the monoclinic space group C2/c (Z=8) with the parameters a=1000.6(2), b=887.8(2), c=926.3(2) pm, β=103.1(1)°, V=0.8016(3) nm³, R1=0.0452, and wR2=0.0721 (all data). The boron–oxygen network is analogous to those of the compounds HP‐MB₃O₅, (M=K, Rb) and exhibits all three structural motifs of borates—BO₃ groups, corner‐sharing BO₄ tetrahedra, and edge‐sharing BO₄ tetrahedra—at the same time. Channels inside the boron–oxygen framework contain the cesium and oxonium ions, which are disordered on a specific site. Estimating the amount of hydrogen by solid‐state NMR spectroscopy and X‐ray diffraction led to the composition HP‐Cs_1?x(H₃O)_xB₃O₅ (x=0.5–0.7), which implies a nonzero phase width.     

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.     

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.     

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.     

Pr(BO2)3 und PrCl(BO2)2: Zwei meta‐Borate des Praseodyms im Vergleich

Pr(BO₂)₃ and PrCl(BO₂)₂: Two Praseodymium meta‐Borates in Comparison Single‐crystalline PrCl(BO₂)₂ can be obtained by the reaction of praseodymium, Pr₆O₁₁ and PrCl₃ with a small excess of B₂O₃ in evacuated silica tubes after seven days at 850 °C. If NaCl is additionally used as flux, single crystals of Pr(BO₂)₃ dominate the main product. Both praseodymium(III) meta‐borates are air and water stable. The crystals of PrCl(BO₂)₂ emerge as long, thin, pale green needles which tend to severe twinning due to their fibrous habit. The crystal structure (triclinic, P1¯; a = 420.56(4), b = 655.42(7), c = 808.34(8) pm, α = 82.361(8), β = 89.173(9), γ = 71.980(7)°, Z = 2) exhibits zigzag chains {[(B1)o^t_1/1O^e_2/2(B2)O^t_1/1O^e_2/2]²⁻} (≡ {[BO₂]⁻}) of corner‐linked [BO₃]³⁻ triangles with syndiotactic orientation of the terminal oxygen atoms which are running parallel to the [100] direction. The Pr³⁺ cations are surrounded by three Cl⁻ and seven O²⁻ anions with the shape of a tetracapped trigonal prism. The green, transparent crystals of Pr(BO₂)₃ (monoclinic, C2/c; a= 984.98(9), b = 809.57(8), c = 641.02(6) pm, β = 126.783(9)°, Z = 4) appear either lath‐shaped or rather spherical. In the crystal structure the B³⁺ cations reside both in trigonal planar as well as in tetrahedral coordination of oxygen atoms. Both types of borate polyhedra ([BO₃]³⁻ and [BO₄]⁵⁻) are linked via corners to form chains of the composition {[(B2)‐O^t_1/1O^e_2/2(B1)O^e_4/2(B2)O^t_1/1O^e_2/2]³⁻} (≡ {[BO₂]⁻}) which run parallel [101]. The coordination sphere of the Pr³⁺ cations consists of ten oxide anions which build up a bicapped square antiprism.     

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 the First Fully Characterized Vanadoborate Na3[B6O9(VO4)]

Single crystals of synthetic Na₃VB₆O₁₃ were obtained by heating a mixture of Na₂CO₃.H₂O, V₂O₅, and H₃BO₃; its formula has been determined by the resolution of the structure from X-ray diffraction data. The compound is orthorhombic, space group P2₁2₁2₁; the unit cell parameters are a=7.723(7), b=10.155(4), c=12.505(4) Å, Z=4. The crystal structure was solved from 1535 reflections until R=0.029; it contains hexaborate units formed by three triangular BO₃ (3Δ) and three tetrahedral BO₄ (3T). These hexaborate groups are joined together to form sheets which are linked by VO₄ tetrahedra leading to a three-dimensional network. The shorthand notation of the vanadoborate ion is 6: ∞³ (3Δ+3T)+VO₄. The sodium atoms are inside the channels that exist in the compound, whose structural formula may be written Na₃[B₆O₉(VO₄)]. This compound melts incongruently; powder may be obtained by annealing a mixture of Na₂B₄O₇ and V₂O₅ at 630°C. It is the first vanadoborate for which the formula and the structure have been unambiguously established.     

LaCl(BO2)2 und Er2Cl2[B2O5]: Zwei Chlorid‐Oxoborate dreiwertiger Lanthanide

LaCl(BO₂)₂ and Er₂Cl₂[B₂O₅]: Two Chloride Oxoborates of Trivalent Lanthanides Er₂Cl₂[B₂O₅] is obtained as single crystals by the reaction of ErCl₃, Er₂O₃ and B₂O₃ with an excess of ErCl₃ as flux in evacuated silica tubes after two weeks at 850 °C. The compound crystallizes as long, pale pink needles and appears to be air‐ and water‐resistant. Single‐crystalline LaCl(BO₂)₂ emerges from the reaction of La₂O₃, LaCl₃, and B₂O₃ with an excess of B₂O₃ as flux in evacuated silica tubes after four weeks at 900 °C. LaCl(BO₂)₂ crystallizes as thin, colourless, air‐ and water‐resistant needles which tend to severe twinning due to their fibrous habit. The crystal structure of Er₂Cl₂[B₂O₅] (orthorhombic, Pbam; a = 1489.65(9), b = 1004.80(6), c = 524.86(3) pm; Z = 4) contains two crystallographically different erbium cations. (Er1)³⁺ resides in pentagonal‐bipyramidal coordination of seven anions while (Er2)³⁺ is surrounded by only six anions with the shape of an octahedron. The planar oxodiborate units [B₂O₅]^4— consisting of two vertex‐shared [BO₃]^3— triangles are isolated according to {([BOO]₂)^4—}. LaCl(BO₂)₂ crystallizes isostructurally with PrCl(BO₂)₂ in the triclinic space group P1¯ (a = 423.52(4), b = 662.16(7), c = 819.33(8) pm; α = 82.081(8), β = 89.238(9), γ = 72.109(7)°; Z = 2). The characteristic unit consists of endless chains built up by corner‐linked [BO₃]^3— triangles. These quasi‐planar zigzag chains of the composition {[(B1)OO(B2)OO]^2—} (≡ {[BO₂]^—} run parallel [100]. The La³⁺ cations exhibit coordination numbers of ten and are coordinated by three Cl^— and seven O^2— anions.     

Solid‐Liquid Equilibria in the Quinary Na+, K+//Cl−, SO2−4, B4O2−7‐H2O System at 298 K

The solid‐liquid equilibria in the quinary system Na⁺, K⁺//Cl^?, SO^2?₄, B₄O^2?₇‐H₂O at 298 K had been studied experimentally using the method of isothermal solution saturation. Solubilities and densities of the solution of the quinary system were measured experimentally. Based on the experimental data, the dry‐salt phase diagram and water content diagram of the quinary system were constructed, respectively. In the equilibrium diagram of the quinary system Na⁺, K⁺//Cl^?, SO^2?₄, B₄O^2?₇‐H₂O at 298 K, there are five invariant points F1, F2, F3, F4 and F5; eleven univariant curves E1F1, E2F2, E3F3, E4F5, E5F2, E6F4, E7F5, F1F4, F2F4 F1F3 and F3F5, and seven fields of crystallization saturated with Na₂B₄O₇ corresponding to Na₂SO₄, Na₂SO₄·10H₂O, Na₂SO₄·3K₂SO₄ (Gla), K₂SO₄, K₂B₄O₇·4H₂O, NaCl and KCl. The experimental results show that Na₂SO₄·3K₂SO₄ (Gla), K₂SO₄ and K₂B₄O₇·4H₂O have bigger crystallization fields than other salts in the quinary system Na⁺, K⁺//Cl^?, SO^2?₄, B₄O^2?₇‐H₂O at 298 K.     

Self‐Assembly of [B‐SbW9O33]9− Subunit with Transition Metal Ions (Mn2+, Cu2+, Co2+) in Aqueous Solution: Syntheses,Structures and Magnetic Properties of Sandwich Type Polyoxometalates with Subvalent SbIII Heteroatom

Rational self‐assembly of Sb₂O₃ and Na₂WO₄, or (NH₄)₁₈[NaSb₉W₂₁O₈₆] with transition‐metal ions (Mn²⁺, Cu²⁺, Co²⁺), in aqueous solution under controlled conditions yield a series of sandwich type complexes, namely, Na₂H₂[Mn_2.5W_1.5(H₂O)₈(B‐β‐SbW₉O₃₃)₂]?32 H₂O (1) , Na₄H₇[Na₃(H₂O)₆Mn₃(μ‐OAc)₂(B‐α‐SbW₉O₃₃)₂]?20 H₂O (OAc=acetate anion) (2) , NaH₈[Na₂Cu₄Cl(B‐α‐SbW₉O₃₃)₂]?21 H₂O (3) , Na₈K[Na₂K(H₂O)₂{Co(H₂O)}₃(B‐α‐SbW₉O₃₃)₂]? 10 H₂O (4) , and Na₅H[{Co(H₂O)₂}₃W(H₂O)₂(B‐β‐SbW₉O₃₃)₂]?11.5 H₂O (5) . These structures are determined by using the X‐ray diffraction technique and further characterized by obtaining IR spectra and performing elemental analysis. Structure analysis reveals that polyoxoanions in 1 and 5 comprise of two [B‐β‐SbW₉O₃₃]^9? building units, whereas 2 , 3 , and 4 consist of two isomerous [B‐α‐SbW₉O₃₃]^9? building blocks, which are all linked by different transition‐metal ions (Mn²⁺, Cu²⁺, or Co²⁺) with different quantitative nuclearity. It should be noted that compound 2 represents the first one‐dimensional sinusoidal chain based on sandwich like tungstoantimonate building blocks through the carboxylate‐bridging ligands. Additionally, 3 is constructed from sandwiched anions [Na₂Cu₄Cl(B‐α‐SbW₉O₃₃)₂]^9? linked to each other to form an infinitely extended 2D network, whereas 5 shows an interesting 3D framework built up from offset sandwich type polyoxoanion [{Co(H₂O)₂}₃W(H₂O)₂(B‐β‐SbW₉O₃₃)₂]^6? linked by Co²⁺ and Na⁺ ions. EPR studies performed at 110 K and room temperature reveal that the metal cations (Mn²⁺, Cu²⁺, Co²⁺) reside in a square‐pyramidal geometry in 2 , 3 , and 4 . The magnetic behavior of 1 – 4 suggests the presence of weak antiferromagnetic coupling interactions between magnetic metal centers with the exchange integral J=?0.552 cm^?1 in 2 .     

Poly[tetrasodium(I)‐tetra‐μ2‐bis(butane‐1,4‐diyldioxy)borato‐μ2‐1,4‐butane­diol]

In the title compound, [Na₄(C₈H₁₆BO₄)₄(C₄H₁₀O₂)]_n, there are two coordination types for the four independent Na⁺ cations: two Na⁺ cations bond to six diolate O atoms [Na—O = 2.305 (2)–2.609 (2) Å], while the other two are five‐coordinate via one 1,4‐butane­diol [2.289 (2) and 2.349 (3) Å] and four diolate O atoms [2.295 (2)–2.408 (2) Å]. Corresponding to this, there are three‐ and four‐coordinate diolate O atoms, the latter bridging Na atoms. The 1,4‐butane­diol mol­ecules lie on inversion centres. The boron stereochemistry shows minor local perturbations from its usual tetrahedral state [B—O = 1.457 (4)–1.503 (4) Å]. The resulting polymer packs as sheets parallel to the (10) plane crosslinked by the butane­diol mol­ecules. The structure was solved using data from a multiple crystal.     

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.     

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).     

Determination of Boron with Isotope Dilution Method

100 ng or less amount of boron in the form of Na₂B₄O₇ was loaded on tantalum filament of thermal ionization mass spectrometer. A serial isotope ratios of metaborate, Me=88 (Na₂ ¹¹BO₂) and Me=89 (Na₂ ¹¹BO₂) prepared with spike (¹⁰B enriched) and nature boron were determined successfully and compared with reference values.     

From β-Na2B6O10 to Na3AlB8O15 and Na3Al2B7O15: Structural Tuning of Anionic-Group Architectures by Substitution of [BO4] by [AlO4] Covalent Tetrahedra

Two new sodium aluminum borates, Na₃AlB₈O₁₅ and Na₃Al₂B₇O₁₅, have been successfully synthesized by the high-temperature solution method. They crystallize in the different space groups, P2₁/c and P2/c, respectively. The B−O configurations of β-Na₂B₆O₁₀, Na₃AlB₈O₁₅ and Na₃Al₂B₇O₁₅ are compared to feature complicated different dimensional open-framework structures caused by the substitution of [BO₄] by [AlO₄] covalent tetrahedra. Moreover, the experimental results indicate that Na₃AlB₈O₁₅ and Na₃Al₂B₇O₁₅ have short ultraviolet (UV) cutoff edges (<187 nm). The first-principles calculations show that Na₃AlB₈O₁₅ and Na₃Al₂B₇O₁₅ have moderate birefringence (0.075 and 0.041@1064 nm, respectively).     

[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.     

Sodium 2‐oxo‐3‐semicarbazono‐2,3‐dihydro‐1H‐indole‐5‐sulfonate dihydrate

The title compound, Na⁺·C₉H₇N₄O₅S⁻·2H₂O, presents a Z configuration around the imine C=N bond and an E configuration around the C(O)NH₂ group, stabilized by two intra­molecular hydrogen bonds. The packing is governed by ionic inter­actions between the Na⁺ cation and the surrounding O atoms. The ionic unit, Na⁺ and 2‐oxo‐3‐semicarbazono‐2,3‐dihydro‐1H‐indole‐5‐sulfonate, forms layers extending in the bc plane. The layers are connected by hydrogen bonds involving the water mol­ecules.     

The role of TiO2 in the B2O3–Na2O–PbO–Al2O3 glass system

Optical and vibrational studies have been carried out on 60B₂O₃·(20−x)Na₂O·10PbO·10Al₂O₃:xTiO₂ (x=0, 1, 2, 3, 4, and 5 mol%) glasses, in order to understand the role of TiO₂ in the 60B₂O₃·20Na₂O·10PbO·10Al₂O₃ glass matrix. The X-ray patterns reveal homogeneous glasses over the entire compositional range. The absorption spectra show that the energy of the optical band gap (ΔE_opt) and Urbach's energy (E_U) decreases as TiO₂ content increases. The changes observed in the Raman and IR spectra are related to the BO₄→BO₃ back conversion effect and the appearance of “loose” BO₄⁻ groups. The data indicate that titanium ions act as a network modifier.