The fluorine atom + hydrazoic acid system:  a chemical source for nitrogen monofluoride(a1.DELTA.)

Habdas, Jan; Wategaonkar, Sanjay; Setser, D. W.

doi:10.1021/j100286a039

Cited by 50 publications

(47 citation statements)

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“…The most obvious advantage 77.4 kcalmol-' [14]. The rate determining step for is generation of the (a 1 A) states in the gas phase this process is reaction (1), which has a room tem- [4][5][6][7][8][9][10] rather than the mixed gas/aqueous chemistry perature rate coefficient [15] hand, the NX(a'A) molecules are much more reactransition was achieved when a small flow of HI is tive than 0 2 (a6A) [11][12][13] CF 3 I in 12 L bulbs. The flow rate of HCl was stored in a stainless steel vessel.…”

Section: Introduction Used For the Generation Of Nci(a'a) Is Summarizedmentioning

confidence: 99%

Temperature dependence of the Cl+HN3 reaction from 300 to 480 K

Manke

Henshaw

Madden

et al. 1999

Chemical Physics Letters

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Section: Introduction Used For the Generation Of Nci(a'a) Is Summarizedmentioning

confidence: 99%

Temperature dependence of the Cl+HN3 reaction from 300 to 480 K

Manke

Henshaw

Madden

et al. 1999

Chemical Physics Letters

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“…The ∆H°f (N 3 ) has been revised upward by two groups later. By observing the HF(v,J) infrared chemiluminescence (IRCL) from F + HN 3 , Setser and coworkers 53 41 based on CCSD(T) and MRCI calculations predict ∆H°f for NCl to be 76.5 kcal mol -1 , in better agreement with the experiment. Here, it should be pointed out that Clyne's estimate for NCl is also a limit and not an absolute measurement.…”

Section: Resultsmentioning

confidence: 84%

Chlorofluoroamines: Ab Initio and DFT Studies on Their Structure, Enthalpies of Formation, and Unimolecular Reaction Pathways

Shamasundar

Arunan

2001

J. Phys. Chem. A

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Ab initio and density functional theory calculations are reported for the chlorofluoroamines HNXY (X/Y ) F/Cl) and all possible unimolecular reaction products from their ground state. Reliable enthalpies of formation for these molecules and reaction products have been calculated using the G2 model. The large discrepancy between theory and experiment over the ∆H°f(NCl) has been resolved by reevaluating the old experimental data. Optimized structures of all the species have been obtained at various levels up to MP2/6-311++G** and B3LYP/6-311++G**. The triplet-singlet energy gaps have been estimated for NH, NF and NCl at various levels. Enthalpies of various reactions have been calculated at advanced levels including PMP4, CBS-Q, G1, G2, and G2-MP2. Transition states (TS) for the three-centered HX elimination reactions have been characterized. Vibrational frequencies for all the reactants, products, and transition states have been calculated using HF, MP2 and DFT methods with 6-311++G** basis set. Threshold energies for the bond dissociation reactions and the HX (X ) F/Cl) elimination reactions have been calculated. RRKM calculations have been carried out with these results to determine the branching ratio for the various possible reactions. The barrier for HCl elimination from HNFCl is 18 kcal mol -1 higher than that of HF elimination. Still, according to DFT results, it is found that the HCl elimination is an important channel because of entropy factors, possibly explaining the experimental observations. However, the MP2 and G2 results predict the HF elimination to be more important for HNFCl. Moreover, the N-Cl bond energies in HNFCl and HNCl 2 are less than the HCl elimination barriers. Hence, the as yet unsuspected N-Cl bond dissociation may be a dominant decomposition pathway for HNFCl and HNCl 2 .

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“…for reaction (i) at 298 K. Additionally, Setser and co-workers [7,[9][10][11] measured the rate constant from the time dependence of the NFA C H T U N G T R E N N U N G (a and obtained similar results, among which (5 AE 2) 10 À11 cm 3 molecule À1 s À1 (at 298 K) for reaction (i) was regarded as the most-accepted value. [7,[9][10][11] A few experiments [8,9,12] indicate that reaction (i) is dominant, although there is no direct measurement of NF (X 3 S À ), which was predicted [9] to be no more than 10 % of the total NF product.…”

mentioning

confidence: 89%

“…Instead, the adiabatic reaction channel on the singlet PES leading to NFA C H T U N G T R E N N U N G (a 1 D) should be the major channel, and similarly, the main pyrolysis products of the singlet FN 3 should be NFA C H T U N G T R E N N U N G (a 1 D) and N 2 , in agreement with the experiments. [8,9,13] As we mentioned in Section 1, the B3LYP calculations of Zeng et al [17] indicate that the crossing point appears before the transition state, and thus, they considered NFA C H T U N G T R E N N U N G (X 3 S À ) as the main pyrolysis product of the singlet FN 3 . It seems that they were not able to locate the geometry of the MECP properly.…”

Section: Nonadiabatic Channel Due To the Pes Intersectionmentioning

confidence: 99%

“…[7,[9][10][11] A few experiments [8,9,12] indicate that reaction (i) is dominant, although there is no direct measurement of NF (X 3 S À ), which was predicted [9] to be no more than 10 % of the total NF product. Moreover, the thermal fragmentation of FN 3 A C H T U N G T R E N N U N G ( 1 A') was found [13] to yield the metastable NFA C H T U N G T R E N N U N G (a 1 D) with high efficiency.…”

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confidence: 99%

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A Theoretical Study of the Mechanism and Kinetics of F+N₃ Reactions

Liu

Bian

et al. 2006

ChemPhysChem

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Both the singlet(1A') and triplet(3A'') potential energy surfaces (PESs) of F+N(3) reactions are investigated using the complete-active-space self-consistent field (CASSCF) and the multireference configuration interaction (MRCI) methods with a proper active space. The minimum energy crossing point (MECP) at the intersection seam between the 1A' and 3A'' PESs is located and used to clarify the reaction mechanisms. Two triplet transition states are found, with one in the cis form and the other one in the trans form. Further kinetic calculations are performed with the canonical unified statistical (CUS) theory on the singlet PES and the improved canonical variational transition-state (ICVT) method on the triplet PES. The rate constants are also reported. At 298 K, the calculated rate constant is in reasonably good agreement with experimental values, and spin-orbit coupling effects lower it by 28 %. The spectroscopic constants derived from the fitted potential-energy curves for the singlet and triplet states of NF are in very good agreement with experimental values. Our calculations indicate that the adiabatic reaction on the singlet PES leading to NF(a(1)Delta)+N(2) is the major channel, whereas the nonadiabatic reaction through the MECP, which leads to NF(X(3)Sigma(-))+N(2), is a minor channel.

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The fluorine atom + hydrazoic acid system: a chemical source for nitrogen monofluoride(a1.DELTA.)

Cited by 50 publications

References 2 publications

Temperature dependence of the Cl+HN3 reaction from 300 to 480 K

Temperature dependence of the Cl+HN3 reaction from 300 to 480 K

Chlorofluoroamines: Ab Initio and DFT Studies on Their Structure, Enthalpies of Formation, and Unimolecular Reaction Pathways

A Theoretical Study of the Mechanism and Kinetics of F+N₃ Reactions

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The fluorine atom + hydrazoic acid system: a chemical source for nitrogen monofluoride(a1.DELTA.)

Cited by 50 publications

References 2 publications

Temperature dependence of the Cl+HN3 reaction from 300 to 480 K

Temperature dependence of the Cl+HN3 reaction from 300 to 480 K

Chlorofluoroamines: Ab Initio and DFT Studies on Their Structure, Enthalpies of Formation, and Unimolecular Reaction Pathways

A Theoretical Study of the Mechanism and Kinetics of F+N3 Reactions

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A Theoretical Study of the Mechanism and Kinetics of F+N₃ Reactions