- Further studies of the tetraborane carbonyl B4H8CO
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Tetraborane-8 carbonyl (B4H8CO) is made by the action of CO on either B4H10 or B5H11, suggesting the processes B4H10 → B4H8 + H2 and B5H11 → B4H8 + BH3. The reversal of these (significant for polyborane interconversion mechanisms) is shown by the high yields of B4H10 and B5H11 obtained when H2 or B2H6 reacts with B4H8CO. Basic reagents attack B4H8CO to form nonvolatiles without liberation of any CO; dimethyl ether and water behave so, and trimethylamine forms some (CH3)3NBH3. Ethylene also fixes the CO, in a slightly volatile unstable compound, (C2H4)4B4H8CO (structure uncertain), whereas BH3CO + 3C2H4 → (C2H5)3B + CO is quantitative. With excess PF3, B5H11 forms BH3PF3 and B4H8PF3, from the latter of which CO reversibly displaces PF3; in these reactions CO is not irreversibly fixed. In support of structural elucidation of B4H8CO by infrared and nuclear magnetic resonance spectra, B4D10, B5D11, and B4D8CO were made in nearly pure form. The structure of B4H8CO remains uncertain but the possibilities are limited. There may be a tautomeric equilibrium such that at least one H atom alternates between two B-H-B bridgings and a terminal B-H situation - much like the tautomerism of B5H11.
- Spielman, John R.,Burg, Anton B.
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- Architecture of lead oxide microcrystals in glass: A laser and etching based method
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Lead oxide is an important glass modifier not only for affecting the chemical and mechanical stabilities of glasses, but also for improving their thermal and optical properties. Since specific properties are associated with the presence of PbO, its crystallization is important to enhance the material performance. Although considerable advances have been achieved regarding the fabrication of glass-ceramic from lead-based glasses, the spatial confinement of the crystallization remains challenging. Direct laser writing (DLW) has been considered an essential technique to overcome this issue, since material properties can be changed in localized and pre-determined regions. Although DLW with femtosecond laser pulses has been widely used for glass processing, its usage for phase transformations and control of the architecture of crystals has not been much exploited. This paper reports the design and control of β-PbO and 3PbO·H2O crystalline phases in a lead borate glass using fs-DLW followed by chemical etching at room temperature. We demonstrated that the etching in aqueous KOH solution is responsible for the glass crystallization, whereas the grooves produced by fs-laser pulses enable the selective crystallization in a pre-determined 2D pattern. The method described herein is important as it can control phase transformation at the micrometer scale and also permits the growth of lead oxide and lead oxide hydrate phases, which are not achieved by heat treatment. The morphologies of these microcrystals correspond to the structure of the respective compounds, being an octahedral euhedral crystal for 3PbO·H2O and thin sheets for β-PbO crystalline phases.
- Almeida,Almeida,Hernandes,Mendon?a
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- Neocarboranes, a new family of stable organoboranes isomeric with the carboranes
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Heating of the recently described compound2 carborane, C2B10H12, at 465-500° for 24 hr. produced the first member of a new family of organoboranes. The name neocarborane has been assigned to this product, which is isomeric with the original carborane. The chemistry ot neocarborane has been explored and is compared to that of carborane. In general, neocarborane derivatives are less polar and more stable than their carborane isomers. As in thecarboranes, the C2B10H10 unit is unusually inert and many standard organic processes can be effected on organofunctional substituents attached to the neocarborane carbon atoms. Carborane is assigned the distorted icosahedral structure, A, with the two carbon atoms sharing a short, depressed edge of an otherwise regular icosahedron. A regular icosahedral structure, C or D, is suggested for neocarborane. Electronic structures and possible reaction paths are indicated.
- Grafstein, Daniel,Dvorak, Joseph
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- Complete dehydrogenation of hydrazine borane and hydrazine catalyzed by MIL-101 supported NiFePd nanoparticles
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Trimetallic NiFePd nanoparticles (NPs) anchored on metal-organic framework (MOF) MIL-101 have been facilely prepared via a simple impregnation method. The as-prepared NiFePd/MIL-101 catalysts have been characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) equipped with energy dispersed X-ray detector (EDX) and selected area electron diffraction (SAED), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), N2 adsorption/desorption isotherms and X-ray photoelectron spectroscopy (XPS) techniques. And the as-synthesized catalysts have been applied for hydrogen generation from aqueous alkaline solution of hydrazine borane (HB, N2H4BH3). Compared to the pure Ni0.36Fe0.24Pd0.4 NPs, MIL-101 supported mono- and bi-metallic counterparts, the Ni0.36Fe0.24Pd0.4/MIL-101 catalyst exhibits much higher catalytic performance for complete conversion of N2H4BH3 to H2 with 100% selectivity at 323 K. The turnover frequency (TOF) value for the dehydrogenation of N2H4BH3 in the presence of Ni0.36Fe0.24Pd0.4/MIL-101 catalyst reaches 60 h?1. Remarkably, the Ni0.36Fe0.24Pd0.4/MIL-101 catalyst also shows high catalytic activity and 100% selectivity towards hydrogen generation from hydrous hydrazine (N2H4·H2O) at 323 K with a TOF value of 40.8 h?1. In addition, the durability tests exhibit that the Ni0.36Fe0.24Pd0.4/MIL-101 catalyst is still highly active in the complete dehydrogenation of N2H4BH3 and decomposition of N2H4·H2O with 100% hydrogen selectivity even after five recycles.
- Yang, Kun,Yang, Kangkang,Zhang, Shiliang,Luo, Yan,Yao, Qilu,Lu, Zhang-Hui
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- Kinetics and Mechanism of Hydrolysis of Some Amine-Cyanoboranes in Acid Perchlorate Media
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In acid media (+> = 0.02-0.2 mol dm-3), isopropylamine- and diisopropylamine-cyanoborane are hydrolysed completely to boric acid, hydrogen, hydrogen cyanide and the salt of the corresponding amine.The reaction occurs in steps, viz.
- Das, Mrinal Kanti,Bandyopadhyay, Soumendra Nath,Bhattacharyya, Siddhartha,Banerjee, Rupendranath
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- Electrical and magnetic properties of nanocrystalline Fe100-xNix alloys
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The electrical and magnetic properties of nanocrystalline binary Fe100-xNix alloys, where x ranges from 0 to 100, prepared by a combination of aqueous and solid-state reduction processes have been studied vis-à-vis their microstructure. The microstructural studies indicate the formation of near-equilibrium phases in the alloys with crystallite size in the range 20-40 nm. The crystallite size in the case of pure Fe and Ni, however, is in the range 40-80 nm. The electrical transport in the temperature range 20-300 K exhibits a typical ferromagnetic metallic behavior in all the cases and the absolute resistivity of nanocrystalline Fe100-xNix alloys decreases monotonically with increasing Ni content. The saturation magnetization of the alloys on the other hand decreases progressively with Ni addition towards that of pure Ni value. The coercivity of alloys is found to be independent of temperature in the range 5-300 K except in the case of pure Ni wherein it increases from 30 Oe at 300 K to 65 Oe at 5 K. The electrical and magnetic properties of the nanocrystaline Fe-Ni alloys do not follow the predictions of simple itinerant band model for alloys. The temperature dependence of saturation magnetization in all the cases has a T3/2 Bloch variation while the average atomic moment of the alloys has an effective medium composition dependence.
- Vitta, Satish,Khuntia,Ravikumar,Bahadur
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- Systematic study of Cr3+ substitution into octahedra-based microporous aluminoborates
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Single crystals of pure aluminoborate PKU-1 (Al3B 6O11(OH)5·nH2O) were obtained, and the structure was redetermined by X-ray diffraction. There are three independent Al atoms in the R3 structure model, and Al3 locates in a quite distorted octahedral environment, which was evidenced by 27Al NMR results. This distortion of Al3O6 octahedra release the strong static stress of the main framework and leads to a symmetry lowering from the previously reported R3 to the presently reported R3. We applied a pretreatment to prepare Al3+/Cr3+ aqueous solutions; as a consecquence, a very high Cr3+-to-Al3+ substitution content (50 atom %) in PKU-1 can be achieved, which is far more than enough for catalytic purposes. Additionally, the preference for Cr3+ substitution at the Al1 and Al2 sites was observed in the Rietveld refinements of the powder X-ray data of PKU-1:0.32Cr3+. We also systematically investigated the thermal behaviors of PKU-1:xCr3+ (0 ≥ x ≥ 0.50) by thermogravimetric-differential scanning calorimetry, in situ high-temperature XRD in vacuum, and postannealing experiments in furnace. The main framework of Cr3+-substituted PKU-1 could be partially retained at 1100 °C in vacuum. When 0.04 ≥ x ≥ 0.20, PKU-1:xCr3+ transferred to the PKU-5:xCr3+ (Al4B6O 15:xCr3+) structure at 750 °C by a 5 h annealing in air. Further elevating the temperature led to a decomposition into the mullite phase, Al4B2O9:xCr3+. For x > 0.20 in PKU-1:xCr3+, the heat treatment led to a composite of Cr 3+-substituted PKU-5 and Cr2O3, so the doping upper limit of Cr3+ in PKU-5 structure is around 20 atom %.
- Li, Qiaoqi,Lin, Cong,Zhou, Zhengyang,Ju, Jing,Li, Guobao,Lin, Jianhua,Gao, Wenliang,Cong, Rihong,Yang, Tao
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- Preparation and properties of H2B2S5 and its decomposition products
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The preparation of solid H2B2S5 and its decomposition product H2S·xBS2, x = 4.84 ± 1.75, and observations of their properties by visual and chemical means and by x-ray, infrared, Raman, and mass spectrometry are reported. Metathioboric acid, (HBS2)3, was prepared by two methods and heated with sulfur in evacuated, sealed Vycor tubes to yield H2S·xBS2. Diiodotrithiadiborolane, I2B2S3, was prepared and treated with H2S to obtain H2B2S5 in benzene solution. Solid H2B2S5 decomposed and polymerized spontaneously to yield H2S·xBS2. X-ray, infrared, and Raman spectrometry revealed polymerization and extensive S-S bonding in the solid. Mass spectrometry of the vapor from the solid products gave predominantly H2B2S5+, H2S+, and their fragments at temperatures below 80°C and then high molecular weight ions up to B8S16+ at higher temperatures. Fragmentation of H2B2S5+ was shown to yield HBS3+ by identification of the corresponding metastable ion. A relationship of H2B2S5 to (BS2)n through polymerization and condensation is proposed.
- Gates, Alfred S.,Edwards, Jimmie G.
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- Chemistry of boranes. VII. Octachlorononaborane-9 and its salts
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Octachlorononaborane-9, B9Cl8H, is a volatile, solid pyrogenic product of H2B10Cl10·xH2O. In aqueous solution B9Cl8H is reduced to the dianion, B9Cl8H-2. Copyright 1964 by the American Chemical Society.
- Forstner,Haas,Muetterties
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- Boron carbide spherical particles encapsulated in graphite prepared by pulsed laser irradiation of boron in liquid medium
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B4 C submicron particles were obtained by laser irradiation of B particles in ethyl acetate under atmospheric pressure and room temperature. Absorbed laser energy brought about B melting and decomposition of surrounding liquid medium molecules, leading to a reaction between the melted B and carbon species to form B4 C. Moreover, the obtained B4 C particles were encapsulated in a graphite layer. Such a graphite surface layer is useful for medical functionalization of particles. Thus, obtained B4 C particles encapsulated in graphite are expected to be promising agents for boron neutron capture therapy.
- Ishikawa, Yoshie,Shimizu, Yoshiki,Sasaki, Takeshi,Koshizaki, Naoto
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- New insights on the mechanism of palladium-catalyzed hydrolysis of sodium borohydride from11B NMR measurements
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To gain insight on the mechanistic aspects of the palladium-catalyzed hydrolysis of NaBH4 in alkaline media, the kinetics of the reaction has been investigated by 11B NMR (nuclear magnetic resonance) measurements taken at different times during the reaction course. Working with BH4- concentration in the range 0.05-0.1 M and with a [substrate]/[catalyst] molar ratio of 0.03-0.11, hydrolysis has been found to follow a first-order kinetic dependence from concentration of both the substrate and the catalyst (Pd/C 10 wt %). We followed the reaction of NaBH4 and its perdeuterated analogue NaBD4 in H2O, in D 2O and H2O/D2O mixtures. When the process was carried out in D2O, deuterium incorporation in BH4 - afforded BH4-nDn- (n = 1, 2, 3, 4) species, and a competition between hydrolysis and hydrogen/deuterium exchange processes was observed. By fitting the kinetics NMR data by nonlinear least-squares regression techniques, the rate constants of the elementary steps involved in the palladium-catalyzed borohydride hydrolysis have been evaluated. Such a regression analysis was performed on a reaction scheme wherein the starting reactant BH4- is allowed both to reversibly exchange hydrogen with deuterium atoms of D2O and to irreversibly hydrolyze into borohydroxy species B(OD)4-. In contrast to acid-catalyzed hydrolysis of sodium borohydride, our results indicate that in the palladium-catalyzed process the rate constants of the exchange processes are higher than those of the corresponding hydrolysis reactions.
- Guella,Zanchetta,Patton,Miotello
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- Polarography of the tetrahydroborate ion. The effect of hydrolysis on the system
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A BH3-containing species, which is a relatively stable intermediate in the hydrolysis of sodium tetrahydroborate (NaBH4) solutions, has an important effect on the polarographic behavior of the system. Controlled potential electrolysis of solutions rich in this species has shown that it is responsible for the anodic polarographic wave at -0.64 v. vs. s.c.e. and that it is oxidized in a three-electron over-all process which yields hydrogen. The presence of an electrooxidizable hydrolysis product explains the abnormal polarographic behavior of unbuffered alkaline NaBH4 solutions and is consistent with other electrochemical studies and nuclear magnetic resonance spectroscopy of partially hydrolyzed solutions.
- Gardiner, John A.,Collat, Justin W.
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- 11B NMR Probes of Copper(II): Finding and Implications of the Cu2+-Promoted Decomposition of ortho-Carborane Derivatives
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The development of noninvasive methodologies for the detection of d-block metal ions such as copper (Cu2+), zinc (Zn2+), and manganese (Mn2+) is important for understanding their biological roles and relationship with diseases. We have been interested in the use of 11B NMR probes for the detection of d-block metal ions, because 11B is an ultratrace element in living systems. o-Carboranes, which consist of ten boron and two carbon atoms, have been applied to numerous drugs and biological active agents. In this work, we found that the o-carborane-pendant cyclens (L3-L5) (cyclen = 1,4,7,10-tetraazacyclododecane) are decomposed in the presence of Mn2+ or Cu2+ in aqueous solution at neutral pH, accompanied by the release of 4-9 equiv. of B(OH)3. Furthermore, it was found that o-carborane derivatives that contain hydroxyl groups instead of a cyclen unit also undergo decomposition in the presence of Cu2+ and the corresponding complexes such as Cu(bpy) to afford 10 equiv. of B(OH)3, as confirmed by 11B NMR spectroscopic analysis and an azomethine-H assay. These reactions are applied to 11B MRI (magnetic resonance imaging) probes for Cu2+.
- Tanaka, Tomohiro,Nishiura, Yukiko,Araki, Rikita,Saido, Takaomi,Abe, Ryo,Aoki, Shin
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- The Stability of Diphosphino-Boryl PBP Pincer Backbone: PBP to POP Ligand Hydrolysis
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Since moisture may frequently be present in many solvents, it is important to know the reactivity of a catalyst against water for catalytic reactions. In order to explore the stability and understand the transformation process of diphosphino-boryl-based PBP pincer platform, [PdCl{B(NCH2PtBu2)2?o-C6H4}] (1) was treated with PdCl2, HB(NCH2PPh2)2?o-C6H4 was reacted with [PdCl2(cod)] (cod=cyclo-octa-1,5-diene) and [Pd2(dba)3] (dba=dibenzylideneacetone), respectively, in the presence of water. Some novel palladium POP complexes, [Pd2Cl2(μ-Cl){μ-κ3-P,O,P?OB(NCH2PtBu2)2?o-C6H4}] (2 a), [Pd4(μ-Cl)2(μ-O)2{μ-κ3-P,O,P?OB(NCH2PPh2)2?o-C6H4}2] (2 b), [Pd2{μ-κ4-P,P,P,P?O(B(NCH2PPh2)2?o-C6H4)2}{μ-κ2-P,P?(NHCH2PPh2)2?o-C6H4}] (3), were obtained. It was found that the PBP pincer backbone can easily be converted into a POP backbone in the presence of water. From the crystal structures of the resultant palladium complexes, possible pincer backbone transformation pathways were discussed.
- Fang, Fei,Xue, Man-Man,Ding, Man,Zhang, Jie,Li, Shujun,Chen, Xuenian
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- The solid-state structure of diboronic acid, B2(OH)4
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The crystal structure of diboronic acid contains molecules of B2(OH)4 hydrogen-bonded into two-dimensional sheets linked by B...O interactions.
- Baber, R. Angharad,Norman, Nicholas C.,Orpen, A. Guy,Rossi, Jean
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- The asymmetric cleavage of diborane by water. The structure of diborane dihydrate
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The dihydrate and diethanolate of diborane have been prepared at -130° and their compositions have been established by stoichiometric measurements. The dihydrate is assigned the structure BH2(H2O)2+BH4- on the basis of low-temperature infrared spectra of the deuterated and nondeuterated species. A study of the evolution of hydrogen from the reaction of diborane with a solution of HCl in a water-methanol mixture at -78° has provided further evidence for the asymmetric cleavage of diborane by water and alcohol.
- Finn, Patricia,Jolly, William L.
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- Hydrothermal-reaction-assisted laser machining of cubic boron nitride
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Although the high hardness and chemical stability of cubic boron nitride (cBN) complicate its machining, the mass decrease of cBN in a steam environment at high temperature has been reported. In this study, we investigated hydrothermal-reaction-assisted laser drilling of cBN in various environments. A single-crystalline cBN grain, binder-containing sintered cBN, and binderless sintered cBN were irradiated with an Ar ion laser in water and steam, and in gas atmospheres. The cBN reacted with water, and NH4+ or NH4+ -N and boric acid were produced. Hydrothermal- reaction-assisted machining was not effective for binder-containing sintered cBN, but was effective for single-crystalline cBN and binderless sintered cBN.
- Hidai, Hirofumi,Tokura, Hitoshi
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- DERIVES MONO ET BICYCLIQUES DU BORE TETRACOORDONNE ET DES α-AMINODIACIDES: REACTIONS AVEC DIVERS NUCLEOPHILES
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Water, methanol and isopropylamine react mono- and bi-cyclic boroxazolidones (2a and 3a) by attacking the boron atom and not the CO group, with formation of aminodiacid and tricoordinated boron compounds.The boron compounds undergo successive B-C cleavage
- Garrigues, Bernard,Mulliez, Michel
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- Kinetics of Reduction of Silver(II) by Sodium Tetrahydroborate
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The kinetics of reduction of silver(II) by sodium tetrahydroborate in aqueous acidic solution has been investigated.The reaction was observed to proceed in two steps, namely, (a) the formation of the intermediate AgI and (b) the subsequent conversion of AgI to Ag0.The activation parameters for the two steps have been separately calculated.The intermediate AgI species, and the final products, were characterized by chemical and spectral methods.A plausible mechanism for the reduction of AgII ions has been proposed.
- Dasgupta, Manash,Mahanti, Mahendra K.
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- A novel profluorescent probe for detecting oxidative stress induced by metal and H2O2 in living cells
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A profluorescent probe that has no fluorescent response to H 2O2, iron or copper ions but can be readily activated in the presence of both H2O2 and Fe (or Cu) ion has been developed; the probe is capable of detecting oxidative stress promoted by Fe (or Cu) and H2O2 (i.e. the Fenton reaction conditions) in living cells.
- Wei, Yibin,Zhang, Yi,Liu, Zhiwei,Guo, Maolin
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- A noble-metal-free nanocatalyst for highly efficient and complete hydrogen evolution from N2H4BH3
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Hydrazine borane (N2H4BH3, 15.4 wt% H) has been considered as a highly promising hydrogen storage material because of its inherent advantages such as high hydrogen content and high stability in the solid state. However, the practical application of N2H4BH3 for the generation of hydrogen is strongly inhibited by the need for expensive noble metal-based catalysts. To overcome this challenge, noble-metal-free CuNiMo nanocatalysts were prepared using a facile chemical reduction approach under an ambient atmosphere at room temperature. Unexpectedly, the resultant CuNiMo catalyst exhibits excellent catalytic activity, and 100% H2 selectivity toward hydrogen generation from N2H4BH3via its BH3 group hydrolysis and N2H4 moiety decomposition at 323 K. To the best of our knowledge, this is the first report of a noble-metal-free catalyst achieving a complete conversion of N2H4BH3 to H2. In addition, CuNiMo can achieve a complete dehydrogenation of hydrous hydrazine (N2H4·H2O). The excellent catalytic performance of the Cu0.4Ni0.6Mo catalyst may be attributed to the electronic modification among Cu, Ni and Mo, and may also be related to the strong basic sites of Cu0.4Ni0.6Mo. The present simple, low cost, highly efficient, and highly selective catalyst may promote the practical application of N2H4BH3 as an effective hydrogen storage material.
- Yao, Qilu,Lu, Zhang-Hui,Zhang, Rui,Zhang, Shiliang,Chen, Xiangshu,Jiang, Hai-Long
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- The synthesis of functional derivatives of the [1-CB9H 10]- anion by Brellochs reaction
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Reactions of decaborane with various aldehydes in alkaline media were studied. The reactions with HCOH and 2-MeOC6H4CHO give the corresponding arachno-carboranes [6-R-arachno-CB9H 13]- (R = H, C6H4-2-OMe), whereas the reactions with C6H5CHO, 4-BrC6H 4CHO, 4-MeCONHC6H4CHO, and 2-SC 4H3CHO result in the nido-carboranes [6-R-nido-CB 9H11]- (R = C6H5, C 6H4-4-Br, C6H4-4-NHCOMe, 2-SC 4H3). Both the arachno- and nido-carboranes can be easily oxidized with elemental iodine in an alkaline aqueous solution giving the corresponding closo-derivatives [2-R-closo-2-CB9H9] -. These closo-2-isomers, under heating in solution, undergo rearrangement to more thermodynamically favorable closo-1-isomers [1-R-closo-1-CB9H9]-. The structure of (Bu 4N)[1-(4-BrC6H4)-1-CB9H 9] was determined using single crystal X-ray diffraction.
- Sivaev, Igor B.,Starikova, Zoya A.,Petrovskii, Pavel V.,Bregadze, Vladimir I.,Sj?berg, Stefan
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- Synthesis and characterization of new 19-vertex macropolyhedral boron hydrides
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The new boron hydride anions 10-R-B19H19- (R = H, Thx) were synthesized by the reaction of M2[B18H20] (M = Na, K) with HBRCl·SMe2 (R = H, Thx) or HBCl2·SMe2 in diethyl ether. The anions are comprised of edge-sharing, nido 10- and 11-vertex cluster fragments, and are characterized by their 11B, 11B{1H}, and 11B-11B COSY NMR spectra. The salt [(Ph3P)2N][B19H20]·0.5THF crystallized in the triclinic space group P1(a = 12.6344-(2) A, b = 13.5978(2) A, c = 14.1401(2) A; α = 77.402(2)°, β = 81.351(2)°, γ = 73.253(2)°). Possible synthetic pathways are discussed. The dianion B19H192- is formed by deprotonation of B19H20- with Proton Sponge (1,8-bis(dimethylamino)naphthalene) in THF, and is identified on the basis of its 11B, 11B{1H}, and 11B-11B COSY NMR spectra.
- Dopke, Joel A.,Powell, Douglas R.,Gaines, Donald F.
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- Acid- and Base-Catalyzed Hydrolytic Hydrogen Evolution from Diboronic Acid
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The efficient production of H2 from hydrogen-rich sources, particularly from water, is a crucial task and a great challenge, both as a sustainable energy source and on the laboratory scale for hydrogenation reactions. Herein, a facile and effective synthesis of H2 and D2 from only acid- or base-catalyzed metal-free hydrolysis of B2(OH)4, a current borylation reagent, has been developed without any transition metal or ligand. Acid-catalyzed H2 evolution was completed in 4 min, whereas the base-catalyzed process needed 6 min. The large kinetic isotopic effects for this reaction with D2O, deuteration experiments and mechanistic studies have confirmed that both H atoms of H2 originate from water using either of these reactions. This new, metal-free catalytic system holds several advantages, such as high efficiency, simplicity of operation, sustainability, economy, and potential further use.
- Wang, Yi,Shen, Jialu,Huang, Yu,Liu, Xiang,Zhao, Qiuxia,Astruc, Didier
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p. 3013 - 3018
(2021/03/26)
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- Detection of hydrogen peroxide using dioxazaborocanes: elucidation of the sensing mechanism at the molecular level by NMR and XPS measurements
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A fluorescent dioxazaborocane was synthesised and characterized, in order to study its turn-off sensing process for hydrogen peroxide detection. The exposure of the dioxazaborocane to diluted vapours of H2O2 led to a strong non reversible quenching of the fluorescence. Both NMR and XPS analyses were carried out before and after exposure of dioxazaborocane to H2O2 vapours. They unequivocally show that the boron atom is oxidised in the film with cleavage of the N-B dative bond. Identification of products such as phenol and boric acid by NMR, supported by consistent XPS data, enabled the whole reaction sequence that explains the fluorescence quenching of dioxazaborocane upon H2O2 exposure to be described accurately. Direct hydrolysis of dioxazaborocane to diol, without oxidation, was only marginally observed.
- Caron, Thomas,Palmas, Pascal,Frénois, Céline,Méthivier, Christophe,Pasquinet, Eric,Pradier, Claire-Marie,Serein-Spirau, Fran?oise,Hairault, Lionel,Montméat, Pierre
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p. 4114 - 4121
(2020/03/19)
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- Nickel-Ceria Nanowires Embedded in Microporous Silica: Controllable Synthesis, Formation Mechanism, and Catalytic Applications
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Designing highly efficient catalysts for use in fuel production is a highly attractive research area but still remains challenging. Herein, for the first time, ultrafine Ni nanoparticles (NPs) self-assembled on ceria nanowires (NWs) and then embedded in a microporous silica shell (denoted as Ni-CeO2?SiO2) are successfully designed and synthesized via a one-pot facile strategy. The average diameter of Ni-CeO2 NWs is just 2.9 nm, and the length is up to 102.7 nm. The resulting Ni-CeO2?SiO2 exhibits high performance and 100% hydrogen selectivity for H2 production from N2H4 and N2H4BH3 in aqueous solution. Unexpectedly, Ni-CeO2?SiO2 also has good catalytic performance and thermal stability for CO2 methanation. The high catalytic performance of Ni-CeO2?SiO2 can be attributed to the synergistic electronic effect and strong interaction between Ni NPs and CeO2 NWs with plenty of oxygen vacancies, as well as the unique structure effect. As an effective strategy, the present work provides an opportunity to embed ultrafine metal NPs-CeO2 NWs into a microporous silica shell, which has broad application prospects in various catalytic fields.
- Feng, Gang,Huang, Meiling,Lu, Zhang-Hui,Yao, Qilu,Zou, Hongtao
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supporting information
p. 5781 - 5790
(2020/04/20)
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- B(C6F5)3- And HB(C6F5)2-mediated transformations of isothiocyanates
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This contribution reports on the reactivity of isothiocyanates towards the boranes B(C6F5)3and HB(C6F5)2. The reactions of alkyl-substituted isothiocyanates with B(C6F5)3were found to result in rearrangement reactions to yield stable thiocyanate-B(C6F5)3adducts. Treatment of isothiocyanates with HB(C6F5)2leads to 1,2-hydroboration and thus, B,N,C,S heterocycles are formed, which react further under non-inert conditions. Hydrolysis of the hydroboration products leads to a new access to thioformamides.
- Fischer, Malte,Schmidtmann, Marc
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supporting information
p. 6205 - 6208
(2020/06/22)
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- Virtues of Volatility: A Facile Transesterification Approach to Boronic Acids
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Boronic acids are an increasingly important compound class for many applications, including C-C bond formation reactions, medicinal chemistry, and diagnostics. The deprotection of boronic ester intermediates is frequently a problematic and inefficient step in boronic acid syntheses. We describe an approach that highly facilitates this transformation by leveraging the volatility of methylboronic acid and its diol esters. The method is performed under mild conditions, provides high yields, and eliminates cumbersome and problematic purification steps.
- Hinkes, Stefan P.A.,Klein, Christian D.P.
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supporting information
p. 3048 - 3052
(2019/05/10)
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- Frustrated Lewis pairs incorporating the bifunctional Lewis acid 1,1′-fc{B(C6F5)2}2: Reactivity towards small molecules
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Applications of the bifunctional ferrocenediyl Lewis acid 1,1′-fc{B(C6F5)2}2 in frustrated Lewis pair (FLP) chemistry are described. The coordination (or otherwise) of a range of sterically encumbered C-, N- and P-centred Lewis bases has been investigated, with lutidine, tetramethylpiperidine, PPh3, PtBu3 and the expanded ring carbene 6Dipp being found to be sterically incapable of coordinate bond formation. The chemistry of a range of these FLPs in the presence of H2O, NH3, CO2 and cyclohexylisocyanate (CyNCO) has been investigated, with the patterns of reactivity identified including simple coordination chemistry, E-H bond cleavage and C-B insertion.
- Tirfoin, Rémi,Gilbert, Jessica,Kelly, Michael J.,Aldridge, Simon
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p. 1588 - 1598
(2018/02/09)
-
- Preparation method of Zr(IV) compound as well as application of Zr(IV) compound to reducing carbon dioxide into methanol
-
A Zr(IV) compound and application thereof to reducing carbon dioxide into methanol comprise the following steps: 1) in a glove box, weighing the Zr(IV) compound Cl3THF2ZrBH4, putting the Zr(IV) compound Cl3THF2ZrBH4 into a Schlenk bottle and adding tetrahydrofuran; 2) taking out the Schlenk bottle from the glove box, connecting with a vacuum line, degassing, connecting the Schlenk bottle with a balloon full of carbon dioxide and reacting at room temperature for 12 hours; and 3) after the reaction, performing hydrolysis to obtain methanol, wherein the yield is 72.5 percent. The preparation method of the Zr(IV) compound Cl3THF2ZrBH4 is simple, low in raw material cost and easy in industrialized amplified production. The Zr(IV) compound can reduce the carbon dioxide into methanol under the conditions of normal temperature and normal pressure, and NaCl and boric acid which are generated in the reaction process can be continuously recycled, so industrial circulation can be realized and theaim of sustainable production can be fulfilled.
- -
-
Paragraph 0047; 0050
(2018/07/06)
-
- AQUEOUS COMPOSITION AND METHOD OF PRODUCING CHLORINE DIOXIDE USING AQUEOUS COMPOSITION
-
An aqueous composition includes an activator, a chlorite ion source, and water. The aqueous composition is alkaline. The aqueous composition produces chlorine dioxide upon contact with an acid. A method of producing chlorine dioxide includes contacting the aqueous composition with an acid.
- -
-
-
- Br?nsted and Lewis Base Behavior of Sodium Amidotrihydridoborate (NaNH2BH3)
-
The reactivity of sodium amidoborane (NaNH2BH3) as a Br?nsted and Lewis base was studied systematically. The [NH2BH3]– anion can act as a proton acceptor or a hydride donor in different types of reactions. In reactions with very weak Br?nsted acids such as cyclopentadiene, ammonia, and pyrazole, the [NH2BH3]– anion acts as a proton acceptor through the lone pair on N. The reactions of [NH2BH3]– with stronger Br?nsted acids are complicated. In the reaction with ammonium chloride or acetic acid, [NH2BH3]– accepts a proton, reforming NH3BH3. However, in the reaction with HCl or methanol, N–B bond cleavage occurs. [NH2BH3]– can also donate hydride in some reactions. The possible mechanisms of these reactions are discussed.
- Chen, Xi-Meng,Li, Huizhen,Yang, Qiu-Yu,Wang, Rui-Rui,Hamilton, Ewan J. M.,Zhang, Jie,Chen, Xuenian
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p. 4541 - 4545
(2017/09/28)
-
- A nanosized aluminoborate (PKU-5) with Cr-centered octahedral framework: Solid-phase synthesis, characterizations and catalytic ammoximation of cyclohexanone to cyclohexanone azine
-
Octahedron-based redox molecular sieves Cr-PKU-5 were synthesized by a two-step template annealing method and used as catalysts for the liquid-phase ammoximation of cyclohexanone. PKU-5 (Al4B6O15) is a novel anhydrous aluminoborate, but difficult to be synthesized due to the severe demands of preparation procedures. Interestingly, Cr-stabilized PKU-5 can be facilely prepared with nano-scaled distribution and large BET surface area by annealing Cr-doped PKU-1 precursors at high temperature. Le Bail fitting of powder XRD patterns demonstrated large amounts of Cr3+ has been incorporated into the framework of PKU-5. Much different with TS-1 redox molecular sieve, Cr-PKU-5 was favorable to produce ketazine in the liquid-phase ammoximation of ketone, rather than oxime. Based on the discussion about reaction pathway, a probable reaction mechanism was proposed to interpret the critical role of Cr-PKU-5 in such a complex multi-step reaction.
- Zhang, Fenhua,Wang, Weilu,Hu, Shixiang,Ma, Xiaotong,Gao, Wenliang,Cong, Rihong,Yang, Tao
-
-
- Hexamethylenetetramine carboxyborane: synthesis, structural characterization and CO releasing properties
-
Carbon monoxide, although widely known as a toxic gas, has received great attention in the past few decades due to its promising role as a medical gas. Several classes of carbon monoxide releasing molecules (CORMs) have been synthesised with many of them having pharmacological activities under physiological conditions. Herein, we report the synthesis and structural characterization of the first example of amine carboxyborane that releases CO under physiological conditions without the aid of inducers. A representative compound hexamethylenetetramine carboxyborane (HMTA-CB) described here has a half-life of 2.7 days and gradually releases CO with the rate constant of 3.0 × 10?6 s?1. Its ability to promote cell growth shows the beneficial effect of slow CO release to supplement CO in small amounts over time.
- Ayudhya,Raymond,Dingra
-
p. 882 - 889
(2017/02/05)
-
- Aqueous phase reforming of glycerol using doped graphenes as metal-free catalysts
-
Boron-doped graphene obtained by pyrolysis at 900°C of the boric acid ester of alginate was found to be the most active graphene among a series of doped and co-doped graphenes to promote the aqueous phase reforming of glycerol at 250°C. This reaction is of interest in the context of valorization of the aqueous wastes of carbohydrate syrups. Control experiments adding to undoped graphene 1 wt% of triphenylborane, tris(pentafluorophenyl)borane or bis(pinacolyl)diborane as models of possible boron atom types present in B-doped graphene, and boric acid that could be present in a residual amount after pyrolysis, show in all cases an increase in the catalytic activity of graphene. B-doped graphene has also activity for glucose aqueous phase reforming. B-doped graphene undergoes deactivation upon reuse, probably due to B leaching. The results show that graphenes are promising metal-free catalysts for aqueous phase reforming and are alternatives to those containing platinum.
- Esteve-Adell, Iván,Crapart, Bertrand,Primo, Ana,Serp, Philippe,Garcia, Hermenegildo
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p. 3061 - 3068
(2017/07/15)
-
- 11B NMR/MRI Sensing of Copper(II) Ions In Vitro by the Decomposition of a Hybrid Compound of a nido-o-Carborane and a Metal Chelator
-
Cu2+is closely correlated with certain types of physiological and pathological events. Therefore, the development of a noninvasive methodology for detecting Cu2+is important for understanding its biological role and relationship with disease. Herein, we report on the development of a Cu2+-specific11B NMR/MRI probe that contains a chelator unit, TriMEDA. The method is based on the rapid complete deboronation of nido-o-carborane by Cu2+under physiological conditions.
- Tanaka, Tomohiro,Araki, Rikita,Saido, Takaomi,Abe, Ryo,Aoki, Shin
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p. 3330 - 3337
(2016/07/22)
-
- Synthesis of Neutral and Charged Trinitromethyl Borohydrides and Their Complexes
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We propose several simple and effective methods for the synthesis of previously unknown trinitromethyl borohydrides and their complexes with simple cyclic ethers and aromatic nitrogen- containing heterocycles, whereas acyclic ethers did not form such complexes. The data from physicochemical investigations showed that these unique compounds contain directly linked oxidizing and reducing fragments. Some transformations of trinitromethylborane complexes were demonstrated, which can occur by cleavage of all types of bonds formed by boron atom in the starting compounds.
- Shitov,Tartakovskii,Ioffe
-
p. 1647 - 1657
(2015/02/05)
-
- A Bioorthogonal Reaction of N-Oxide and Boron Reagents
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The development of bioorthogonal reactions has classically focused on bond-forming ligation reactions. In this report, we seek to expand the functional repertoire of such transformations by introducing a new bond-cleaving reaction between N-oxide and boron reagents. The reaction features a large dynamic range of reactivity, showcasing second-order rate constants as high as 2.3×103 M-1 s-1 using diboron reaction partners. Diboron reagents display minimal cell toxicity at millimolar concentrations, penetrate cell membranes, and effectively reduce N-oxides inside mammalian cells. This new bioorthogonal process based on miniscule components is thus well-suited for activating molecules within cells under chemical control. Furthermore, we demonstrate that the metabolic diversity of nature enables the use of naturally occurring functional groups that display inherent biocompatibility alongside abiotic components for organism-specific applications. The bond-cleaving reaction between N-oxide and diboron reagents features second-order rate constants as high as 2.3×103 M-1 s-1. Diboron reagents display minimal cell toxicity at millimolar concentrations, penetrate cell membranes, and reduce N-oxides inside mammalian cells. This new bioorthogonal reaction is thus well-suited for chemically activating molecules within cells.
- Kim, Justin,Bertozzi, Carolyn R.
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supporting information
p. 15777 - 15781
(2016/01/29)
-
- Optimization of dissolution of ulexite in phosphate acid solutions
-
The Taguchi optimization method was used to determine optimum conditions for the dissolution of ulexite in phosphate acid solutions. Reaction temperature, solid-to-liquid ratio, phosphate acid concentration, reaction time, particle size and stirring speed
- Doan, Tuba Hatice,Yartai, Ahmet
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p. 601 - 605
(2015/01/16)
-
- Substituent effects on oxidation-induced formation of quinone methides from arylboronic ester precursors
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A series of arylboronic esters containing different aromatic substituents and various benzylic leaving groups (Br or N+Me3Br -) have been synthesized. The substituent effects on their reactivity with H2O2 and formation of quinone methide (QM) have been investigated. NMR spectroscopy and ethyl vinyl ether (EVE) trapping experiments were used to determine the reaction mechanism and QM formation, respectively. QMs were not generated during oxidative cleavage of the boronic esters but by subsequent transformation of the phenol products under physiological conditions. The oxidative deboronation is facilitated by electron-withdrawing substituents, such as aromatic F, NO2, or benzylic N+Me 3Br-, whereas electron-donating substituents or a better leaving group favor QM generation. Compounds containing an aromatic CH 3 or OMe group, or a good leaving group (Br), efficiently generate QMs under physiological conditions. Finally, a quantitative relationship between the structure and activity has been established for the arylboronic esters by using a Hammett plot. The reactivity of the arylboronic acids/esters and the inhibition or facilitation of QM formation can now be predictably adjusted. This adjustment is important as some applications may benefit and others may be limited by QM generation. Tunable quinone methide formation: Aromatic substituents and the benzylic leaving group strongly affect the H 2O2-induced formation of quinone methides (QMs) from arylboronic esters (see scheme). The reactivity of arylboronic esters can be predictably adjusted by varying substituents. Copyright
- Cao, Sheng,Christiansen, Robin,Peng, Xiaohua
-
p. 9050 - 9058
(2013/07/26)
-
- Suzuki-Miyaura cross-coupling of potassium alkoxyethyltrifluoroborates: Access to aryl/heteroarylethyloxy motifs
-
The introduction of an alkoxyethyl moiety onto aromatic substructures has remained a long-standing challenge for synthetic organic chemists. The main reasons are the inherent instability of alkoxyethylmetallic species and the lack of general procedures to access them. A new method utilizing a cross-coupling strategy based on the exceptional properties of organotrifluoroborates has been developed, and the method allows an easy and efficient installation of this unit on a broad range of aryl and heteroaryl bromides.
- Fleury-Bregeot, Nicolas,Presset, Marc,Beaumard, Floriane,Colombel, Virginie,Oehlrich, Daniel,Rombouts, Frederik,Molander, Gary A.
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supporting information
p. 10399 - 10408
(2013/01/15)
-
- Synthesis and characterization of platinasilsesquioxane complexes and their reaction with arylboronic acid
-
Phenyl(iodo)platinum complexes having a 2,2′-bipyridine (bpy) or 1,2-bis(diphenylphosphino)ethane (dppe) ligand react with incompletely condensed silsesquioxane (c-C5H9)7Si7O 9(OH)3 in the presence of Ag2O to yield platinasilsesquioxane complexes [Pt{(c-C5H9) 7Si7O10(OH)2}(C6H 5)(L)] (1, L = bpy; 2, L = dppe). NMR spectroscopy revealed their square-planar structures with an O-coordinated silsesquioxanate ligand and O-H...O hydrogen bonds within the ligand. Both complexes undergo transmetalation of p-methoxyphenylboronic acid to afford unsymmetrical diarylplatinum complexes [Pt(C6H4OCH3-p)(C 6H5)(L)] (3, L = bpy; 4, L = dppe).
- Mintcheva, Neli,Tanabe, Makoto,Osakada, Kohtaro
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p. 187 - 190
(2011/02/27)
-
- Plastic crystalline lithium salt with solid-state ionic conductivity and high lithium transport number
-
Plastic crystallinity of lithium salt, [LiB(OCH2CH 2OCH3)4] (1), and its solid-state ionic conductivity are disclosed. The addition of small amounts of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to borate 1 led to the drastic increase of the ionic conductivity and lithium transport number of the electrolyte.
- Moriya, Makoto,Kato, Daiki,Sakamoto, Wataru,Yogo, Toshinobu
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supporting information; body text
p. 6311 - 6313
(2011/07/09)
-
- Certification of a boron carbide powder reference material for chemical analysis
-
The certification of a boron carbide reference material for chemical composition is described. The mass fractions of 16 elements and two boron species are certified in an international interlaboratory comparison with 35 participating laboratories from six different countries. Beside chemical characterization the certification process includes homogeneity and stability testing of the candidate material boron carbide (type F360, 305M422). Details of the analytical methods used for chemical characterization and of the calculation of the uncertainties of the certified mass fractions are given. The new reference material ERM-ED102 with certified mass fractions of 18 parameters (elements and species) and of the amount fraction of the isotope 10B is a valuable tool for laboratories working in the field of advanced ceramic materials analysis to improve their analytical results.
- Matschat, Ralf,Dette, Angelika,Richter, Silke,Recknagel, Sebastian,Barth, Peter
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p. 4009 - 4016
(2012/02/05)
-
- Multitechnique approach to reveal the mechanism of copper(II)-catalyzed arylation reactions
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Multipleinsitu and time-resolved spectroscopic techniques (EDXAFS,UV-vis, EPR,and NMR), with a focus on simultaneously acquired EDXAFS and time-resolved UV-vis, are described to reveal detailed structural and electronic information on reaction intermediates of an important Cu(II)-catalyzed N-arylation of imidazole. The N-arylation of imidazole was performed in a NMP/H2O solvent mixture, at ambient temperature and atmosphere, using the commercially available Cu catalyst [Cu(OH)(TMEDA)]2Cl2 (I). The spectroscopic study resulted in the characterization of most reaction intermediates, and a novel mechanism for the Cu(II)-catalyzed arylation reaction is proposed. The first and selectivity-determining step is the reaction of the dimeric Cu(II) starting complex with imidazole, forming a mononuclear Cu(II)(imidazole) intermediate, II. After subsequent addition of phenylboronic acid, we propose the formation of a Cu(III)(imidazolate)(phenyl) intermediate, III, which after reductive elimination forms the phenylimidazole product, and a known Cu(I) monomeric species, IV, is identified. Finally, this Cu species is reoxidized, forming back an equilibrium mixture of Cu(II) mononuclear and dinuclear complexes. Inhibition of the reaction by imidazole and phenylimidazole is observed. The phenylboronic acid is, in combination with H2O, involved in the oxidation and reoxidation steps in the described catalytic cycle.
- Tromp, Moniek,Van Strijdonck, Gino P. F.,Van Berkel, Sander S.,Van Den Hoogenband, Adri,Feiters, Martinus C.,De Bruin, Bas,Fiddy, Steven G.,Van Der Eerden,Van Bokhoven, Jeroen A.,Van Leeuwen, Piet W. N. M.,Koningsberger, Diederik C.
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p. 3085 - 3097
(2010/10/04)
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- X-ray diffraction and micro-raman study of structural transformations in (B2O3)1-x(H2O)x glasses and liquids
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Liquid water and vitreous B2O3 are the endpoints of a continuous range of random networks in which hydrogen bonds gradually replace covalent bonds. Previous work has shown that glasses can be obtained by quenching in the range x≤0.50. We report the wide-angle X-ray scattering by the liquid phase in the composition range from x=0.38 to 1.00 (pure water) at temperatures just above the liquidus. The first sharp diffraction peak (FSDP) remains at an approximately constant position in the range 0≤x≤0.8. Beyond this range, the position of the FSDP shifts linearly to higher angles. The relative concentration of the molecular species in the glasses and melts were measured with micro-Raman spectroscopy. Small molecular species are found for glasses and liquids with x;gt&0.36, determining the critical point at which the sample ceases to be a single macromolecule. Molecular water is present in liquids with x;>0.62.
- Bruening, Ralf,Galbraith, Justine B.,Braedley, Katherine E.,Johnstone, Jonathan,Robichaud, Jacques,Balaji, Subramanian,Djaoued, Yahia
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p. 3745 - 3751
(2011/02/16)
-
- New synthetic and structural studies on nitroso-ortho-carboranes RCB10H10CNO and bis(ortho-carboranyl)amines (RCB10H10C)2NH (R = Ph or Me)
-
Improved procedures are reported for the preparation of nitroso-carboranes RCb°NO (Cb° = 1,2-C2B10H10; R = Ph, Me at cage carbon C2) in 44-77% yield, and of dicarboranylamines (RCb°)2NH in 55-65% yield by reacti
- Fox, Mark A.,MacBride, J.A. Hugh,Peace, Richard J.,Clegg, William,Elsegood, Mark R.J.,Wade, Kenneth
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p. 789 - 795
(2009/07/25)
-
- Synthesis and reactivity of [c/oso-1-CB9H9-1-N 2]: Functional group interconversion at the carbon vertex of the {c/oso-1-CB9} Cluster
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The dinitrogen derivative [c/oso-1-CB9H9-1-N2] (1) was prepared from amine [c/oso-1-CB9H9-1-NH3] (2) and reacted with three types of nucleophiles: activated arenes (phenolate and aniline), divalent su
- Rinqstrand, Bryan,Kaszynski, Piotr,Franken, Andreas
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p. 7313 - 7329
(2009/12/08)
-
- Transmetalation of arylpalladium and platinum complexes. Mechanism and factors to control the reaction
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This article reviews recent studies on intra- and intermolecular transfer of the aryl ligand bonded to Pd(II) and Pt(II). Cationic arylpalladium complexes with bpy and THF ligands undergo intermolecular aryl group transfer to produce biaryl via a diarylpalladium intermediate. This reaction is applied to cyclization of cationic dinuclear arylpalladium complexes, affording the crown ether derivative with biphenylene units. Analogous arylplatinum complexes do not form diaryl complexes via transmetalation, while they react with CO and phenylallene to cause replacement of the coordinated solvent and insertion of the small molecules into the Pt-C bond, respectively. Conproportionation of PtCl2(cod) and PtPh2(cod) produces PtCl(Ph)(cod), which is induced by dissociation of a Cl ligand from the former complex. PtCl2(cod) reacts also with diarylplatinum complexes with bpy and dppe. Disproportionation of PtPh(CH2COMe)(cod) and conproportionation of PtPh2(cod) and Pt(CH2COMe)2(cod) take place at 50 °C, but the rates of apparently reversible reactions differ from each other. Addition of OH- to a solution of PtI(Ph)(cod) causes intermolecular phenyl ligand transfer to produce PtPh2(cod). The dinuclear intermediate complex with bridging OH ligand is prepared from an independent route and fully characterized. The complex causes transmetalation of aryl group of aryl boronic acid.
- Suzaki, Yuji,Yagyu, Takeyoshi,Osakada, Kohtaro
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p. 326 - 342
(2008/02/03)
-
- An unprecedented polyborate ester anion: X-ray diffraction studies on [1,8-C10H6(NMe2)2H][B 5O6(OMe)4]
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The slow hydrolysis of B(OMe)3 in a CH2Cl2 solution in the presence of 1,8-C10H6(NMe 2)2 (5:1 ratio) led to the formation of the novel isolated pentaborate ester anion [B5O6(OMe)4] -, which was characterized by a single-crystal X-ray diffraction study as the salt [1,8-C10H6(NMe2) 2H][B5O6(OMe)4].
- Beckett, Michael A.,Bland, Catherine C.,Horton, Peter N.,Hursthouse, Michael B.,Varma, K. Sukumar
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p. 3801 - 3803
(2008/10/09)
-
- Synthesis and reactivity of a platinum(II) complex with a chelating dehydro(arylboronic anhydride) ligand. Transmetalation of arylboronic acid
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The reaction of ArB(OH)2 (Ar = C6H4OMe-4, Ph, C6H4COMe-4) with PtI2(dppe) in THF in the presence of Ag2O and H2O at room temperature produced a Pt complex with a chelating dehydro(arylboronic anhydride) ligand, Pt(OBArOBArO)(dppe) (1a, Ar = C6H4OMe-4; 1b, Ar = Ph; 1c, Ar = C6H4COMe-4). The complexes were characterized by NMR spectroscopy and X-ray crystallography. Reactions of protonic acids, such as HCl, CF3COOH, and CH3COOH, with 1a yielded complexes with chloro and carboxylate ligands, PtX2(dppe) (2, X = Cl; 3, X = OCOCF3; 4, X = OCOMe). The complexes 1a - c react with arylboronic acids bearing the same aryl group as the ligands of the complexes to form diarylplatinum complexes, PtAr2(dppe) (5a, Ar = C6H 4OMe-4; 5b, Ar = Ph; 5c, Ar = C6H4COMe-4), respectively. Reactions of 4-MeCOC6H4B(OH)2 with Ib and of PhB(OH)2 with 1c in 2:1 molar ratios form mixtures of three diarylplatinum complexes in a statistical ratio.
- Pantcheva, Ivayla,Osakada, Kohtaro
-
p. 1735 - 1741
(2008/10/09)
-
- Synthesis of scandium orthoborate powders
-
Two polymorphs of scandium orthoborate, ScBO3, are synthesized by adding aqueous ammonia to aqueous solutions of scandium nitrate and boric acids and calcining the resulting precipitates. Dehydration of the precipitates reaches completion below
- Tkachenko,Fedorov,Kuznetsov,Voronov,Lavrishchev,Shukshin,Yarotskaya,Kononova
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p. 171 - 175
(2008/10/09)
-
- 1-Oxa-nido-dodecaborate [OB11H12]- from the controlled oxidation of the closo-borates [B11H 11]2- and [B12H12]2-
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The closo-dodecaborate [B12H12]2 is degraded at room temperature by oxygen in an acidic aqueous solution in the course of several weeks to give B(OH)3. The degradation is induced by Ag2+ ions, generated from Ag+ by the action of H 2S2O8. Oxa-nido-dodecaborate(1-) is an intermediate anion, that can be separated from the reaction mixture as [NBz1Et3][OB11H12] after five days in a yield of 18 %. The action of FeCl3 on the closo-undecaborate [B 11H11]2- in an aqueous solution gives either [B22H22]2- (by fusion) or nido-B 11H13(OH)- (by protonation and hydration), depending on the concentration of FeCl3. In acetonitrile, however, [B11H11]2- is transformed into [OB 11H12]- by Fe3+ and oxygen. The radical anions [B12H12].- and [B 11H11].- are assumed to be the primary products of the oxidation with the one-electron oxidants Ag2+ and Fe 3+, respectively. These radical anions are subsequently transformed into [OB11H12]- by oxygen. The crystal structure analysis shows that the structure of [OB11H 12]- is derived from the hypothetical closo-oxaborane OB12H12 by removal of the B3 vertex, leaving a non-planar pentagonal aperture with a three-coordinate O vertex, as predicted by NMR spectra and theory.
- Volkov, Oleg,Paetzold, Peter,Hu, Chunhua
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p. 945 - 948
(2008/10/09)
-
- Chemical properties of mononuclear and dinuclear phenylplatinum(II) hydroxo complexes with cod ligands. Transmetalation of arylboronic acids, coupling of the phenyl ligands, and carbonylation
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The reaction of bpy with [{Pt(Ph)(cod)}2(μ-OH)](BF 4) (1-BF4; cod = 1,5-cyclooctadiene) in acetone splits a Pt-O bond to yield a mixture of Pt(CH2COMe)(Ph)(cod) (2) and [Pt(Ph)(bpy)(cod)](BF4) (3-BF4), whereas a similar reaction in toluene produces 3-BF4 and Pt(OH)(Ph)(cod) (4). The complex 4 was obtained in solution and was not isolated as analytically pure crystals because of its gradual disproportionation, giving PtPh2(cod) (5). The dinuclear complex 1-BF4 reacts with ArB(OH)2 (Ar = Ph, C6H2F3-2,4,6) to form 5 and Pt(C 6H2F3-2,4,6)(Ph)(cod) (6), respectively, via aryl group transfer from boron to platinum. The accompanying formation of B(OH)3 has been confirmed by 11B{1H} NMR spectroscopy. The reaction of BF3·Et2O with 1-BF4 followed by the addition of NH4Cl(aq) produces biphenyl and PtCl2(cod), which takes place possibly via a dinuclear intermediate. The cationic dinuclear complex 1-BF4 reacts with CO (1 atm) to form benzophenone. Since the reactions of AgBF4 with Pt-(COPh)(I)(cod) (7) and CO with [Pt(Ph)(THF)(cod)](BF4) also yield benzophenone, the above carbonylation of 1-BF4 is considered to involve mononuclear intermediates.
- Suzaki, Yuji,Osakada, Kohtaro
-
p. 3251 - 3258
(2008/10/09)
-
- HETEROCYCLIC DERIVATIVES AND THEIR USE AS THERAPEUTIC AGENTS
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Methods of treating an SCD-mediated disease or condition in a mammal, preferably a human, are disclosed, wherein the methods comprise administering to a mammal in need thereof a compound of formula (I): where x, y, G, J, K, L, M, V R2, R3, R4, R5, R5a, R6, R6a, R7, R7a, R8 and R8a are defined herein. Pharmaceutical compositions comprising the compounds of formula (I) are also disclosed.
- -
-
Page/Page column 48
(2010/10/20)
-
- Synthesis, structure, and reactivity of 13-vertex carboranes and 14-vertex metallacarboranes
-
Syntheses, properties, and synthetic applications of 13-vertex closo- and nido-carboranes are reported. Reactions of the nido-carborane salt [(CH 2)3C2B10H10]Na 2 with dihaloborane reagents afforded 13-vertex closo-carboranes 1,2-(CH2)3-3-R-1,2-C2B10H 10 (R = H (2), Ph (3), Z-EtCH=C(Et) (4), E-tBuCH= CH (5)). Treatment of the arachno-carborane salt [(CH2)3C 2B10H10]Li4 with HBBr 2·SMe2 gave both the 13-vertex carborane 2 and a 14-vertex closo-carborane (CH2)3C2B 12H12 (8). On the other hand, the reaction of [C 6H4(CH2)2C2B 10H10]Li4 with HBBr2·SMe 2 generated only a 13-vertex closo-carborane 1,2-C6H 4(CH2)2-1,2-C2B11H 11 (9). Electrophilic substitution reactions of 2 with excess Mel, Br2, or I2 in the presence of a catalytic amount of AlCl3 produced the hexa-substituted 13-vertex carboranes 8,9,10,11,12,13-X6-1,2-(CH2)3-1,2-C 2B11H5 (X = Me (10), Br (11), I (12)). The halogenated products 11 and 12 displayed unexpected instability toward moisture. The 13-vertex closo-carboranes were readily reduced by groups 1 and 2 metals. Accordingly, several 13-vertex nido-carborane dianionic salts {nido-1,2-(CH 2)3-1,2-C2B11H11}{Li 2(DME)2-(THF)2} (13), [{nido-1,2-(CH 2)3-1,2-C2B11H11}{Na 2(THF)4}]n (13a), [{nido-1,2-(CH 2)3-3-Ph-1,2-C2B11H 10}-{Na2(THF)4}]n (14), [{nido-1,2-C6H4(CH2)2-1,2-C 2B11H11}{Na2(THF)4}] n (15), and {nido-1,2-(CH2)3-1,2-C 2B11H11}{M(THF)5} (M = Mg (16), Ca (17)) were prepared in good yields. These carbon-atom-adjacent nido-carboranes were not further reduced to the corresponding arachno species by lithium metal. On the other hand, like other nido-carborane dianions, they were useful synthons for the production of super-carboranes and supra-icosahedral metallacarboranes. Interactions of 13a with HBBr2·SMe2, (dppe)NiCl2, and (dppen)NiCl2 gave the 14-vertex carborane 8 and nickelacarboranes [η5-(CH2)3C 2B11H11]Ni(dppe) (18) and [η5- (CH2)3C2B11H11]Ni(dppen) (19), respectively. All complexes were fully characterized by various spectroscopic techniques and elemental analyses. Some were further confirmed by single-crystal X-ray diffraction studies.
- Deng, Liang,Chan, Hoi-Shan,Xie, Zuowei
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p. 5219 - 5230
(2007/10/03)
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- Borane adducts of the water soluble phosphine PTA (PTA = 1,3,5-triaza-7-phosphaadamantane)
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Boronation of the water soluble phosphine PTA (PTA = l,3,5-triaza-7- phosphaadamantane) in dry THF easily affords the N-boronated adduct N-B-PTABH3 which represents the first N-coordinated adduct of this popular water soluble phosphine (N-B-PTABH3 = 1-boranyl-1,3,5-triaza- 7-phosphaadamantane). In situ 31P NMR spectroscopy suggests the occurrence of a stepwise boronation resulting in the addition of as many as four equivalents of BH3 to PTA to give the polyboranyl species N x, Py-B-PTA(BH3)(x+y) (x = 1-3, y = 0, 1). Hydrolysis of the monoboranyl adduct occurs slowly in the presence of water yielding back PTA and boric acid, H3BO3.
- Bola?o, Sandra,Albinati, Alberto,Bravo, Jorge,Gonsalvi, Luca,Peruzzini, Maurizio
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p. 360 - 363
(2008/10/09)
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- Synthetic and reaction chemistry of heteroatom stabilized boryl and cationic borylene complexes
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The synthesis, spectroscopic and structural characterization of the aryloxy and amino functionalized chloroboryl complexes (η5-C 5R5)Fe(CO)2B(OMes)Cl (R = H, 2a; R = Me, 3a) and (η5-C5H5)Fe(CO)2B(N iPr2)Cl (7a) are reported. Compound 2a is shown to be a versatile substrate for further boron-centred substitution chemistry leading to the asymmetric boryl complexes (η5-C5H 5)Fe(CO)2B(OMes)ERn [ERn = OC 6H4tBu-4, 2c; ERn = SPh, 2d] with retention of the metal-boron bond. The reactivities of 2a, 3a and 7a towards the halide abstraction agent Na[BArf4] have also been examined, in order to investigate the potential for the generation of cationic heteroatom-stabilized terminal borylene complexes. The application of this methodology to the mesityloxy derivatives 2a and 3a gives rise to B-F containing products, presumably via fluoride abstraction from the [BArf 4]- counter-ion. By contrast, amino-functionalized complex 7a is more amenable to this approach, and the thermally robust terminal aminoborylene complex [(η5-C5H5)Fe(CO) 2B(NiPr2)][BArf4] (9) can be isolated in ca. 50% yield. The reactivity of 9 towards a range of nucleophilic and/or unsaturated reagents has been examined, with examples of addition, protonolysis and metathesis chemistries having been established. The Royal Society of Chemistry 2006.
- Kays, Deborah L.,Rossin, Andrea,Day, Joanne K.,Ooi, Li-Ling,Aldridge, Simon
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p. 399 - 410
(2007/10/03)
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- Conjugates of polyhedral boron compounds with carbohydrates. 2. Unexpected easy closo- to nido-transformation of a carborane-carbohydrate conjugate in neutral aqueous solution
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A novel 1,2-dicarba-closo-dodecaborane-lactose conjugate 4c, when dissolved in water or methanol, is subject to unexpected deboronation in neutral conditions leading to the formation of the corresponding nido-counterpart (5) as detected by 11B NMR spectroscopy. After heating the aqueous solution of the conjugate 4c at 60 °C for 17 h pure 1,2-dicarba-nido-undecaborane- lactose conjugate 5 was obtained.
- Kononov, Leonid O.,Orlova, Anna V.,Zinin, Alexander I.,Kimel, Boris G.,Sivaev, Igor B.,Bregadze, Vladimir I.
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p. 2769 - 2774
(2007/10/03)
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- Study of the heteropolyacid H21B3W39O 132 · nH2O
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The heteropolyacid H21B3W39O132 · H2O (B3W39) was studied by solid-state IR spectroscopy and differential thermal analysis and by 183W, 17O, and 11B NMR in solution. The NMR spectra of the B3W39 anion, which consists, according to structural data, of three equivalent BW13 fragments, confirmed the integrity of the HPA in solutions but revealed the deviation from the C s and C3h symmetry determined previously, which results in structure chirality. Potentiometric titration showed the nonequivalence of the HPA protons, only 11 of which are strongly acidic. Concentrated (≥0.05 M) solutions of HPA are unstable; after several days, H5BW 12O40 and tungstic acid can be isolated from the solutions. On heating, solid B3W39 starts to decompose into the same products below 200°C. Copyright
- Maksimov,Maksimovskaya,Litvak
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p. 1062 - 1065
(2008/10/09)
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- Anthranilamides and methods of their use
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The present invention is related to anthranilamides of formula I, in which R(1) to R(7) have the meanings indicated herein, a process for their preparation, their use as medicaments, and pharmaceutical preparations containing them. The compounds act on the Kv1.5 potassium channel and inhibit a potassium current which is referred to as the ultra-rapidly activating delayed rectifier in the atrium of the human heart. The compounds are therefore suitable for use as novel antiarrhythmic agents for the treatment and prophylaxis of atrial arrhythmias (e.g., atrial fibrillation (AF) or atrial flutter).
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