BaB2O3F2: A Barium Fluorooxoborate with a Unique [B2O3F]− Layer and Short Cutoff Edge

Substitution of oxygen by fluorine in the borate group offers a materials platform from which intriguing structure and functionality may arise. Herein, we report a new fluorooxoborate, BaB₂O₃F₂, synthesized by introducing the F atoms into the BaO–B₂O₃ system. BaB₂O₃F₂ exhibits a unique oxyfluoride layer [B₂O₃F]⁻ and a deep-ultraviolet cutoff edge below 180 nm. The effect of the introduction of F atoms on the structure and optical property of the borate group has been investigated; this should be useful to further expand borate chemistry and materials.     

Na3B3O3F6: Synthesis,Crystal Structure,and Ionic Conductivity

Crystalline Na₃B₃O₃F₆ was synthesized from H₃BO₃ and NaBF₄ at 623 K, alternatively NaBO₂ can be reacted with NaBF₄ at 673 K. The title compound (C2/c, a = 11.866(7), b = 6.901(4), c = 9.367(6) Å, β = 113.724(9)°) contains the cyclo‐fluorooxotriborate anion B₃O₃F₆^3–, which displays a planar B₃O₃ ring. Within the margins of experimental error, its point group symmetry is D_3h. Layers of fluorinated boroxine rings and sodium atoms are stacked in an alternating manner in parallel to the ab plane. The novel sodium fluorooxoborate is a poor sodium ion conductor with conductivities of 8.7 × 10^–5 and 3.6 × 10^–3 S · cm^–1 at 523 and 623 K, respectively.     

Hydrothermal synthesis and crystal structures of two novel acentric mixed alkaline earth metal berylloborates Sr3Be2B5O12(OH) and Ba3Be2B5O12(OH)

The synthesis and structure of the isostructural acentric compounds Sr(3)Be(2)B(5)O(12)(OH) (1) and Ba(3)Be(2)B(5)O(12)(OH) (2) are reported for the first time. These compounds crystallize in the space group R3m, and the unit cell parameters are a = 10.277(15) ? and c = 8.484(17) ? for 1 and a = 10.5615(15) ? and c = 8.8574(18) ? for 2. The structures consist of a network of [Be(2)B(4)O(12)(OH)] units interwoven with a network consisting of MO(9) polyhedra (M = Sr, Ba) and BO(3) triangles and exemplify how acentric building blocks such as [BO(3)](3-), [BO(4)](5-), and [BeO(4)](6-) can be especially suitable to build noncentrosymmetric long-range structures. Both networks are centered on the 3-fold rotation axis and present themselves in alternating fashion along [001]. Acentricity is imparted by the alignment of the polarities of BO(3) and BeO(4) environments. Infrared spectroscopy has been used to confirm the local geometries of B and Be, as well as the presence of hydroxide in the crystal structure. Another interesting feature of these compounds is the presence of disorder involving Be and B at the tetrahedral Be site. The degree of the disorder has been confirmed by observing a noticeable shortening of average Be-O bond distances.     

Dynamic parameters of the hypervalent O3B...O bond

The results of investigations of the common and distinctive features of various chemical bonds, including intermolecular bonds, were considered. The geometries, atom charges, and force constants of the bonds in a dependent system of coordinates were calculated for five boroxide molecular species using the MINDO/3 method. The correlations found between the force constants and the bond energies in the O₃B...O bridge were compared with the analogous relations for the OH...O bridge. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2237–2241, December, 1999.     

Multiphoton dissociation of C3F6O

Major characteristics of multiphoton absorption and multiphoton dissociation of hexafluoropropene oxide (HFPO) were studied. Spectral relationships of the average number of IR photons absorbed per molecule and the yield of multiphoton dissociation were determined in the range of 1040-985 cm^–1 at different laser fluences. At the laser line 1025.3 cm^–1, the effect of collisions with buffer gases on the HFPO multiphoton absorption and multiphoton dissociation was studied and theq-factor was determined (q = O.6 at= 0.55J cm^–2). Characteristic features of HFPO decomposition under collisional conditions (p _HFPO> 0.1 Torr) were discussed. An anomalous difference in the values for quantum efficiency of multiphoton dissociation for long-wave and short-wave wings of HFPO absorption band was revealed. A procedure for correlating the experimental and theoretical data on the yield of multiphoton dissociation (when theq-factor is unknown) was suggested, and corresponding calculations were performed for the frequency 989.6 cm^–1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1927–1932, November, 1994.     

SrB5O7F3 Functionalized with [B5O9F3]6− Chromophores: Accelerating the Rational Design of Deep‐Ultraviolet Nonlinear Optical Materials

Fluorooxoborates, benefiting from the large optical band gap, high anisotropy, and ever‐greater possibility to form non‐centrosymmetric structures activated by the large polarization of [BO_xF_4?x]^(x+1)? building blocks, have been considered as the new fertile fields for searching the ultraviolet (UV) and deep‐UV nonlinear optical (NLO) materials. Herein, we report the first asymmetric alkaline‐earth metal fluorooxoborate SrB₅O₇F₃, which is rationally designed by taking the classic Sr₂Be₂B₂O₇ (SBBO) as a maternal structure. Its [B₅O₉F₃]^6? fundamental building block with near‐planar configuration composed by two edge‐sharing [B₃O₆F₂]^5? rings in SrB₅O₇F₃ has not been reported in any other borates. Solid state ¹⁹F and ¹¹B magic‐angle spinning NMR spectroscopy verifies the presence of covalent B?F bonds in SrB₅O₇F₃. Property characterizations reveal that SrB₅O₇F₃ possesses the optical properties required for deep‐UV NLO applications, which make SrB₅O₇F₃ a promising crystal that could produce deep‐UV coherent light by the direct SHG process.     

NH4Be2BO3F2 and γ‐Be2BO3F: Overcoming the Layering Habit in KBe2BO3F2 for the Next‐Generation Deep‐Ultraviolet Nonlinear Optical Materials

KBe₂BO₃F₂ (KBBF) is still the only practically usable crystal that can generate deep‐ultraviolet (DUV) coherent light by direct second harmonic generation (SHG). However, applications are hindered by layering, leading to difficulty in the growth of thick crystals and compromised mechanical integrity. Despite efforts, it is still a great challenge to discover new nonlinear optical (NLO) materials that overcome the layering while keeping the DUV SHG available. Now, two new DUV NLO beryllium borates have been successfully designed and synthesized, NH₄Be₂BO₃F₂ (ABBF) and γ‐Be₂BO₃F (γ‐BBF), which not only overcome the layering but also can be used as next‐generation DUV NLO materials with the shortest type I phase‐matching second‐harmonic wavelength down to 173.9 nm and 146 nm, respectively. Significantly, γ‐BBF is superior to KBBF in all metrics and would be the most outstanding DUV NLO crystal.     

INDO calculations on the [Be3O(HCO2)3]+ ion configuration

SCF–MO–LCAO–INDO calculations show that the total energy of the [Be₃O(HCO₂)₃]⁺ ion, which is the base peak in the mass spectra of the beryllium μ₄-oxoformato complex, depends on the deviation of the ion configuration from planarity. The planar form is shown to have the lowest energy. The results obtained confirm the suggestion that steric interactions are the major factor governing fragmentations of beryllium μ₄-oxocarboxylato complexes under electron impact.     

Rubidium metaborate,Rb3B3O6

Rubidium metaborate, Rb₃B₃O₆, was obtained by the reaction of Rb₂CO₃ and BN using a radiofrequency furnace at a maximum reaction temperature of 1173 K. The crystal structure has been determined by single‐crystal X‐ray diffraction. The space group is , with all atoms positioned on a twofold axis (Wyckoff site 18e). The ionic compound is isotypic with Na₃B₃O₆, K₃B₃O₆ and Cs₃B₃O₆.     

MO-SCF calculations for B2O3

The results of ab-initio molecular self-consistent field calculations with atomic optimized Gaussian bases are reported for the B₂O₃ molecule. These distinguish between several plausible structures and yield a V-shaped structure as the minimum energy geometry.This work was supported by the National Science Foundation program of Research Participation for College Teachers, Grant No. GY-5404, and by the Air Force Office of Scientific Research, Grant No. AFOSR-68-1438.     

BaIr0,67Be0,33O3: Eine stabilisierte kubische Form von BaIrO3

Inhaltsübersicht. Es ist gelungen, ein durch BeO stabilisiertes Bariumoxoiridat der Zusammensetzung BaIr_0,67Be_0,33O₃ in der Kristallform eines kubischen Perowskits mit kleiner Elementarzelle erstmals darzustellen. Raumgruppe O¹_h–Pm3m, a = 4,1009 Å, Z = 1. Ir⁵⁺ und Be² + besetzen die Oktaederposition des Perowskits statistisch. BaIr_0,67Be_0,33O₃: A Stabilized Cubic Form of BaIrO₃ For the first time it was possible to prepare a new barium-oxoiridate of the formula BaIr_0,67Be_0,33O₃, stabilized by BeO. It crystallizes in a small cubic unit cell of the perovskite type. Space group O¹_h–Pm3m; a = 4.1009 Å; Z = 1. Ir⁵⁺ and Be²⁺ occupy the octahedra positions of the perovskite structure statistically.     

Contribution a l'etude de la determination de Be,B, C,N, O et F par activation au moyen de p,d,3He et α

The activation of these elements, homogeneously contained in a medium thicker than the path length, of slowing-down capacity close to that of aluminium, was determined as a function of energy by irradiating standards with p, d,³He and α particles of energies between: 5 and 15 MeV for protons, 5 and 20 MeV for deuterons and³He particles, 25 and 42 MeV for α particles. The detection sensitivities intrinsically possible in these energy ranges are deduced from the curves obtained. The results apply to all materials through a simple relationship taking into account the path lengths. They may be used in particular to foresee the possibilities offered by activation with these charged particles, from the viewpoint of sensitivity, when the samples to be analysed are irradiated with a beam of given intensity and energy lying between the above limits.     

Synthesis and Crystal Structure of the Strontium Beryllate Sr3Be2O5

Beryllates show an interesting and diverse structural chemistry, resembling that of well-investigated silicates. The coexistence of tetrahedral and trigonal coordination of Be by O atoms in oxoberyllates allows for an even broader variety of structural motives and implies a plurality of possible atomic ratios Be:O in ternary or higher compounds. We have now synthesized the novel strontium oxoberyllate Sr₃Be₂O₅ via a high-temperature high-pressure reaction and have structurally characterized the ternary oxide by single-crystal and powder X-ray diffraction analysis. Sr₃Be₂O₅, a low condensed oxoberyllate, contains unprecedented [Be₂O₅]^6– double triangles and Sr atoms in both double-capped trigonal-prismatic and octahedral coordination. These motifs show striking resemblance to α-SrBeO₂ and SrO, combining their structural properties. Lattice energy (MAPLE) calculations corroborate found parallels to the known phases SrO and α-SrBeO₂.     

Thermal decomposition of the perfluorinated peroxides CF3OC(O)OOC(O)F and CF3OC(O)OOCF3

Gas phase thermal decomposition of CF(3)OC(O)OOC(O)F and CF(3)OC(O)OOCF(3) was studied at temperatures between 64 and 98 degrees C (CF(3)OC(O)OOC(O)F) and 130-165 degrees C (CF(3)OC(O)OOCF(3)) using FTIR spectroscopy to follow the course of the reaction. For both substances, the decompositions were studied with N(2) and CO as bath gases. The rate constants for the decomposition of CF(3)OC(O)OOC(O)F in nitrogen and carbon monoxide fit the Arrhenius equations k(N)2 = (3.1 +/- 0.1) x 10(15) exp[-(29.0 +/- 0.5 kcal mol(-1)/RT)] and k(CO) = (5.8 +/- 1.3) x 10(15) exp[-(29.4 +/- 0.5 kcal mol(-1)/RT)], and that for CF(3)OC(O)OOCF(3) fits the equation k = (9.0 +/- 0.9) x 10(13) exp[-(34.0 +/- 0.7 kcal mol(-1)/RT)] (all in units of inverted seconds). Rupture of the O-O bond was shown to be the rate-determining step for both peroxides, and bond energies of 29 +/- 1 and 34.0 +/- 0.7 kcal mol(-1) were obtained for CF(3)OC(O)OOC(O)F and CF(3)OC(O)OOCF(3). The heat of formation of the CF(3)OCO(2)(*) radical, which is a common product formed in both decompositions, was calculated by ab initio methods as -229 +/- 4 kcal mol(-1). With this value, the heat of formation of the title species and of CF(3)OC(O)OOC(O)OCF(3) could in turn be obtained as Delta(f) degrees (CF(3)OC(O)OOC(O)F) = -286 +/- 6 kcal mol(-1), Delta(f) degrees (CF(3)OC(O)OOCF(3)) = -341 +/- 6 kcal mol(-1), and Delta(f) degrees (CF(3)OC(O)OOC(O)OCF(3)) = -430 +/- 6 kcal mol(-1).