13283-31-3Relevant articles and documents
SmB6 nanoparticles: Synthesis, valence states, and magnetic properties
Bao, Lihong,Chao, Luomeng,Li, Yingjie,Ming, Ming,Yibole,Tegus
, p. 19 - 23 (2015)
Nanocrystalline SmB6 particles were synthesized by the solid-state reaction of Sm2O3/SmCl3 with NaBH4 in the temperature range of 1000-1200 °C. The phase composition, grain morphology, microstructure and valence states of SmB6 were investigated by using XRD, FESEM, HRTEM and XANES. It is interestingly found that the SmB6 nanocrystalline particles with size of 50 nm are easily prepared by using SmCl3 as raw material. The FFT patterns of HRTEM images reveal that the SmB6 nanocrystalline particles have a high crystallinity with cubic structure. The XANES results show that the valence state of Sm is more likely Sm3+. The magnetic measurement shows that the SmB6 nanoparticles show paramagnetic behavior, but there is a small anomaly in the paramagnetic state. The present synthesis technique is novel and invaluable for developing highly crystallized SmB6 nanoparticles.
Gas-Phase Reaction Kinetics of BH
Rice, Jane K.,Caldwell, N. J.,Nelson, H. H.
, p. 3600 - 3605 (1989)
Ground-state BH, generated from the photodissociation of BH3CO at 193 nm and monitored by laser-induced fluorescence, is reacted with NO, H2O, O2, CO2, CO, H2, CH4, C3H8, C2H4, and (CH3)2C=C(CH3)2 at 298 K.Values of the absolute rate constants for these reactions were extracted from observed BH concentration decay profiles (units of cm3 s -1): NO (1.35 +/- 0.20) x 10-10; H2O, (9.75 +/- 1.64) x 10-12; O2, (8.08 +/- 1.20) x 10-13; CO2, (2.64 +/- O.41) x 10-14; C3H8, (7.57 +/- 1.34) x 10-15; C2H4, (1.17 +/- 0.18) x 10-10; (CH3)2C=C(CH3)2, (1.87 +/- 0.30) x 10-10.The indicated ucertainties are +/- (2? plus estimated uncertainties in the measurement).An upper limit of 10-16 cm3s-1 is placed on the rate constant for reaction with CH4.The measured rate constants for the reaction of BH with CO and H2 show a dependence on total pressure.For the reaction BH + H2, we observe a large portion of the falloff region and are able to fit the data using the expression developed by Troe, leading to an estimated value for the limiting high-pressure rate constant of (3.67 +/- 0.91) x 10-13 cm3s-1.For the reaction of BH with CO, measured rate constants could not be extrapolated to the high-pressure limit and therefore were modeled by using a transition-state theory-RRKM approach.
IN-SITU FTIR EMISSION SPECTROSCOPY ON CHEMICAL VAPOUR DEPOSITION PROCESSES
Hopfe, V.,Wagner, D.,Klobes, P.,Herzig, S.,Marx, G.
, p. 115 - 130 (1990)
Infrared emission spectroscopy is a suitable method of detecting transient species in the gas phase and on the surface of growing layers inside a chemical vapour deposition process.The required high level of spectroscopic data results in the refinement of IR Fourier spectroscopy, the optimization of measuring conditions and the application of special modulation and spectra processing techniques.Results of the gas voronizing process of steel from BCl3/H2 mixtures and of the deposition of silicon carbide hard coatings from methyltrichlorosilane show the advantages of these techniques.In the gas phase transient species are detectable, e.g.HBCl2, H2BCl, BCl2 in the boron system and SiCl2, SiCl3, CH3, SiH2, Si2H4 in the silicon system, respectively.While on the metalic ironboride layer B-H, B-Cl and Fe-Cl species are found.
Observation of the gas-phase infrared spectrum of BH3
Kawaguchi, Kentarou,Butler, J. E.,Yamada, Chikashi,Bauer, S. H.,Minowa, Tatsuya,et al.
, p. 2438 - 2441 (1987)
The gas-phase spectrum of BH3 was detected for the first time by diode laser spectroscopy through the observation of the ν2 band.The borane was produced by photolysis of B2H6 or BH3CO with an ArF excimer la,ser.The same spectrum was obtained by a discharge in a B2H6 and He mixture.Line assignments were made for the Q-branch series with J = K of the ν2 band; effects due to Coriolis perturbations by the ν4 state were recognized.
Photodissociation Dynamics of BH3CO at 193 nm
Weiner, Brad R.,Pasternack, L.,Nelson, H. H.,Prather, K. A.,Rosenfeld, R. N.
, p. 4138 - 4142 (1990)
The photodissociation dynamics of the reaction BH3CO --> BH3 + CO at 193 nm have been investigated by using time-resolved infrared absorption spectroscopy and ultraviolet/visible emission spectroscopy.Partitioning of the available energy into the translational and vibrational degrees of freedom has been measured for the nascent CO photofragment.Time-resolved carbon monoxide laser absorption spectroscopy has been used to observe the CO photofragment in vibrationals levels v'' = 0-4.The nascent CO photofragment can be characterized by a vibrational temperature, Tvib = 2760 +/- 160 K.A lower limit to the CO translational energy, Etrans(v''=0) >= 5 kcal/mol, has been established by measuring the Doppler profile of two CO absorption lines with a tunable diode laser absorption system.Time-resolved tunable diode laser absorption spectroscopy has also been employed to observe internal excitation in the nascent BH3 photofragment, as well as measure the quantum yield for its production from BH3CO photolysis.A lower limit for the quantum yield, Φ193(BH3) >= 0.7+0.3-0.2, has been established.By comparison with limiting case models, we conclude that the photodissociation of BH3CO at 193 nm leads to a nonstatistical partitioning of energy into the BH3 fragment.
Photoionization studies of (BH3)n (n= 1,2)
Ruscic, B.,Mayhew, C. A.,Berkowitz, J.
, p. 5580 - 5593 (1988)
The results of photoionization mass spectrometric studies on B2H6, and BH3 ( produced by pyrolysis of B2H6) are presented.The photoion yield curves of B2Hn+ (n = 2-6) and BHn+ (n = 2-3) from B2H6, as well as BHn+ (n = 1-3) from BH3 have been obtained.It is shown that the combination of appearance potential measurements for BH3+ (B2H6) and BH3+ (BH3) yields a poor upper limit for -ΔH dimerization,0 K (BH3) of 52.7 kcal/mol, while the combination of BH2+ (B2H6) and BH2+ (BH3) provides a better upper limit (46.6+/-0.6 kcal/mol) for this quantity.However, the threshold for BH+ (BH3), combined with auxiliary data, provides the best current experimental value, ( 34.3-39.1 )+/-2 kcal/mol.This experimental value is in good agreement with a recent ab initio calculation, and is arrived at by using the best current estimate of ΔHf(B2H6), rather than a radically different value proposed in that paper.The ionization potential of BH3, ΔHf (BH2+), and the atomization energy of BH3 obtained experimentally are in excellent agreement with other ab initio calculations.The upper limits on heats of formation for the ionic species B2Hn+ ( n = 2-6) are obtained, and plausible structures are discussed for these species, based on the current energetics and various ab initio calculations.Finally, the fragmentation behavior of photoions from diborane is shown to have a more facile explanation by quasiequilibrium theory than by a molecular orbital picture, with the probable exception of BH3+ (B2H6).
Single-pot synthesis of zinc nanoparticles, borane (BH3) and closo-dodecaborate (B12H12)2- using LiBH 4 under mild conditions
Ghanta, Sekher Reddy,Rao, Muddamarri Hanumantha,Muralidharan, Krishnamurthi
, p. 8420 - 8425 (2013)
Reduction of ZnCl2 using LiBH4 in mesitylene yielded zinc nanoparticles (Zn-NPs), borane (BH3) and closo-dodecaborate (B12H12)2-. The BH3 evolved gas was trapped as Ph3/sub
Hidden Boron Catalysis: Nucleophile-Promoted Decomposition of HBpin
Bage, Andrew D.,Hunt, Thomas A.,Thomas, Stephen P.
supporting information, (2020/05/18)
Simple nucleophiles with structural similarities to known hydroboration catalysts can readily mediate the formation of BH3 and borohydride species from pinacolborane (HBpin). Alkyne and alkene hydroboration reactions were successfully mediated by nucleophiles through BH3 generation, with BH3-catalyzed hydroboration found to dominate catalysis. NMR spectroscopy and kinetic analyses showed that the nucleophiles NaOtBu, Na[N(SiMe3)2], nBu2Mg, and nBuLi only promoted the formation of BH3 and were not "true" hydroboration catalysts.
NOVEL 3, 4-PROPYLENEDIOXYTHIOPHENE DERIVATIVES WITH PENDANT FUNCTIONAL GROUPS
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Page/Page column 9-10, (2010/11/24)
The present invention relates to the syntheses of 3,4-propylenedioxythiophenes of the formula (I) wherein R represents a n-valent linear or branched, optionally substituted, aliphatic C1-Cn radical and Y represents a pendant functional group. Further, methods for the preparation of the said compounds are disclosed.
Poisoning of heterogeneous, late transition metal dehydrocoupling catalysts by boranes and other group 13 hydrides
Jaska, Cory A.,Clark, Timothy J.,Clendenning, Scott B.,Grozea, Dan,Turak, Ayse,Lu, Zheng-Hong,Manners, Ian
, p. 5116 - 5124 (2007/10/03)
Borane reagents are widely used as reductants for the generation of colloidal metals. When treated with a variety of heterogeneous catalysts such as colloidal Rh, Rh/Al2O3, and Rh(0) black, BH 3· THF (THF = tetrahydrofuran) was found to generate H 2 gas with the concomitant formation of a passivating boron layer on the surface of the Rh metal, thereby acting as a poison and rendering the catalyst inactive toward the dehydrocoupling of Me2NH-BH3. Analogous poisoning effects were also detected for (i) colloidal Rh treated with other species containing B-H bonds such as [HB-NH]3, or Ga-H bonds such as those present in GaH3-OEt2, (ii) colloidal Rh that was generated from Rh(I) and Rh(III) salts using borane or borohydrides as reductants, and (iii) for other metals such as Ru and Pd. In contrast, analogous poisoning effects were not detected for the catalytic hydrogenation of cyclohexene using Rh/Al2O3 or the Pd-catalyzed Suzuki cross-coupling of PhB(OH)2 and Phl. These results suggest that although this poisoning behavior is not a universal phenomenon, the observation that such boron layers are formed and surface passivation may exist needs to be carefully considered when borane reagents are used for the generation of metal colloids for catalytic or materials science applications.
