- Infrared band intensities of bromine nitrate, BrONO2
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The integrated band intensities at 296 K of gaseous bromine nitrate (BrONO2) in the spectral range 500-2000 cm-1 have been measured using Fourier-transform absorption spectroscopy. The absorption spectra were calibrated to absolute a
- Orphal, Johannes,Morillon-Chapey, Mireille,Guelachvili, Guy
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- Gas-Phase Structures of Chlorine Nitrate and Bromine Nitrate (ClONO2 and BrONO2)
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The gas-phase structure of chlorine nitrate was determined by joint analysis of electron diffraction intensities and rotational constants.The structure of bromine nitrate was derived from electron diffraction data alone.Both nitrates have planar structures, and the following geometric parameters were obtained (ra distances in angstroms and angles in degrees; error limits are 2? values and include a possible scale error of 0.1percent for BrONO2): for ClONO2, ra(N=O) = 1.196(1), ra(N-O) = 1.499(3), ra(O-Cl) = 1.673(2), (O=N=O) = 132.6(5), (O-N=Oc) =118.6(3), (O-N=Ot) = 108.8(3), (N-O-Cl) = 113.0(3); for BrONO2, ra-((N=O) = 1.205(3), ra(N-O) = 1.456(5), ra(O-Br) = 1.829(4), (O=N=O) = 133.9(8), (O-N=Oc) = 119.5(6), (O-N=Ot) = 106.6(5), (N-O-Br) = 113.9(8).The gas-phase structure for ClONO2 is compared to the crystal structure and to ab initio predictions.The results for both compounds are discussed together with those of other covelent nitrates XONO2 with X = H, Me, Et, and O2N.
- Casper, Bernd,Lambotte, Peter,Minkwitz, Rolf,Oberhammer, Heinz
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- crystal structure of bromine nitrate brono2
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The crystal structure of bromine nitrate BrONO2 has been determined on a single crystal with MoKα radiation at -83°C. The structure is orthorhombic, space group P212121, Z = 4, and the cell dimensions are a = 403.2(2), b = 684.9(4), c = 1201.4(5) pm. An intermolecular Br.....O contact leads to the formation of chains within the crystal. Attempts to synthesize a bromine(III)-nitrate by oxidizing CF3Br and CCl3Br with ClONO2 were not successful.
- Minkwitz, Rolf,Hertel, Thomas
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- Heterogeneous hydrolysis and reaction of BrONO2 and Br2O on pure ice and ice doped with HBr
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The rate of uptake of bromine nitrate (BrONO2) and dibromine monoxide (Br2O) on different types of ice, such as condensed (C), bulk (B), and single-crystal ice (SC) have been investigated in a Teflon-coated Knudsen flow reactor in the temperature range 180-210 K using mass spectrometric detection. For the whole temperature range the Br2O uptake kinetics is first order in [Br2O] with a mean initial uptake coefficient of γ0 = 0.24 ± 0.10, which leads to the exclusive formation of HOBr. The BrONO2 hydrolysis has been measured on B-,C-, and SC-type ice and leads to HOBr and Br2O on all types of ice. At a fixed temperature the rate law is first order in [BrONO2] with γ ≈ 0.3 at 180 K. The observed negative temperature dependence for the heterogeneous hydrolysis of BrONO2 on pure ice leads to Ea of -2.0 ± 0.2, -2.1 ± 0.2, and -6.6 ± 0.3 kcal/mol on C-, B- and SC-type ice, respectively. Despite the high reactivity of BrONO2 on ice substrates, the kinetics of interaction of BrONO2 on ice nevertheless depends on the type of ice used. No saturation of the uptake coefficient has been observed during the BrONO2 hydrolysis on ice in contrast to the ClONO2/ice system. On ice samples doped with approximately 5 × 1016 molecules HBr per cm3 the kinetics of the interaction of BrONO2 with HBr leads to an uptake coefficient similar to that for BrONO2 hydrolysis. The interaction of BrONO2 with HBr occurs via the hydrolysis of BrONO2 to HNO3 and HOBr where the latter reacts with HBr in a fast secondary reaction to produce Br2 with Ea = -1.2 ± 0.2 kcal/mol.
- Aguzzi, Arnaud,Rossi, Michel J.
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p. 5891 - 5901
(2007/10/03)
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- Rate Coefficients for the Thermal Decomposition of BrONO2 and the Heat of Formation of BrONO2
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Rate coefficients (k-7) for the thermal decomposition of bromine nitrate, BrONO2 + M -> BrO + NO2 + M, have been obtained at temperatures between 320 and 340 K and pressures between 100 and 1000 Torr.These data are combined with recommended values for the reverse reaction to obtain an equilibrium constant for the reaction pair, KP,7 = 5.44E-9 exp(14192/T) atm-1, and a heat of reaction for the thermal dissociation of 28.2 +/- 1.5 kcal/mol at 298 K.This reaction enthalpy is used in conjunction with literature data to arrive at a consistent set of ΔH0f(298 K) data for BrONO2 (10.1 +/- 2.0 kcal/mol), BrO (30.4 +/- 2.0 kcal/mol), HOBr (-14.1 +/- 2.0 kcal/mol), and Br2O (27.3 +/- 2.0 kcal/mol).Additional measurements were made to determine the rate coefficient for Br atom reaction with BrONO2 (k11) relative to the rate coefficient for its reaction with CH3CHO (k12) at 298 K: k11/k12 = 12.5 +/- 0.6.This relative rate measurement yields a rate coefficient of (4.9 +/- 1.5)E-11 cm3 molecule-1 s-1 for k11, using the currently recommended value for k12.Approximate rate constant for reaction of NO (reaction 17) and BrNO (reaction 19) with BrONO2 were also obtained: k17 = 3E-19 cm3 molecule-1 s-1, k19 > 1E-16 cm3 molecule-1 s-1.
- Orlando, John J.,Tyndall, Geoffrey S.
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p. 19398 - 19405
(2007/10/03)
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- Photochemical Decay Reactions of N2O5, HNO3, ClNO3 and BrNO3 in the Energy Range 10-20 eV.
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The photochemical behaviour of gaseous N2O5, HNO3, ClNO3 and BrNO3 has been investigated in the energy range 10-20 eV by photoionization mass spectrometry using monochromatized synchrotron radiation.The decay reactions are analyzed using the photoion yield curves of fragment ions and their appearance energies.Hitherto unknown photochemical reactions and thermochemical data have been evaluated. Keyword Mass Spectrometry / Photochemistry / Photoionization, Dissoziative / Spectroscopy, VUV
- Jochims, H.-W.,Denzer, W.,Baumgaertel, H.,Loesking, O.,Willner, H.
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p. 573 - 578
(2007/10/02)
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- Bromine nitrates
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The reaction of BrF5 with a large excess of LiNO3 at 0°C produces LiF, BrONO2, N2O5, and O2 as the principal products. The infrared spectra of BrONO2 in the gas and solid phases and in N2 and Ne matrices and the Raman spectrum of the solid phase were recorded. With the exception of the N-OBr torsional mode, all fundamental vibrations of BrONO2 can be assigned and support a planar structure for this molecule. The fundamental vibrations involving the NO2 group exhibit pronounced frequency shifts on going from the gas to the solid, indicating association in the solid phase. With N2O5 the BrONO2 molecule forms an unstable adduct, which was shown by Raman spectroscopy to possess the ionic structure NO2+[Br(ONO2)2]-. On the basis of a comparison of our results with those found in the literature and in three unpublished dissertations, it is concluded that the previously reported compounds BrO2·3NO2, Br(NO3)3, and BrNO3·N2O5 are all identical with our material and therefore must be assigned the composition NO2+[Br(ONO2)2]-. For comparison, Cs+[Br(ONO2)2]- was also prepared, and its vibrational spectra were recorded and assigned.
- Wilson, William W.,Christe, Karl O.
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p. 1573 - 1580
(2008/10/08)
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