Molecular structure of dinitrogen pentoxide in the gas phase. Large amplitude motion in a system of coupled rotors

McClelland, Bruce W.; Hedberg, Lise; Hedberg, Kenneth; Hagen, Kolbjørn

doi:10.1021/ja00350a006

Cited by 49 publications

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“…In agreement with the structural data [5] the double bonds between the four oxygen atoms and the two nitrogen atoms in N 2 O 5 were equal to 0.1188 nm, and the bonds between the oxygen atom at the center of the molecule and the nitrogen atoms were equal to 0.1498 nm. The angle between the central oxygen atom and the nitrogen atoms was equal to 111.8°and the angle between the nitrogen atoms and the outer oxygen atoms was equal to 133.2°.…”

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confidence: 87%

“…The angle between the central oxygen atom and the nitrogen atoms was equal to 111.8°and the angle between the nitrogen atoms and the outer oxygen atoms was equal to 133.2°. The authors of [5] concluded that the energy of the molecular structure of N 2 O 5 was minimal when the two torsional angles of rotation t 1 = t 2 » 30°(structure with symmetry C 2 , see Fig. 1c).…”

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confidence: 99%

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Quantum-chemical DFT calculations of the molecular structure of N2O5 in the gas and solid phases

et al. 2007

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By functional density quantum-chemical method (DFT/B3LYP using the 6-311++G(3df)) it has been shown that the molecular structures of N 2 O 5 with C s and C 2 symmetries are energetically equivalent. It follows from calculations of the vibrational frequencies that both structures are characterized by potential energy minima and correspond to stationary states of the N 2 O 5 molecule. It is proposed, on the basis of a comparison of the calculated and experimental vibrational spectra of N 2 O 5 , that dinitrogen pentaoxide exists in the gas phase as an equimolecular mixture of N 2 O 5 molecules with C s and C 2 symmetry, while in the solid phase it is characterized by the C 2 molecular structure.Key words: the functional density method, quantum chemical calculations, molecular structure, N 2 O 5 . N 2 O 5 was first obtained in 1840 as a result of the reaction of AgNO 3 with Cl 2 . Currently the characteristic reaction for the preparation of N 2 O 5 is the reaction of NO 2 with ozone. The finding of N 2 O 5 in the stratosphere of the Earth indicates an important role of gaseous N 2 O 5 in the nitrogen cycle for the destruction of the ozone layer, so that studies of the reactivity and electronic structure of N 2 O 5 has been carried out intensively [1,2].Nitric anhydride (dinitrogen pentaoxide, N 2 O 5 ) exists as colorless, transparent, easily decomposed (at 32°C) crystals. In the solid state N 2 O 5 has a crystalline structure formed of NO 2 + and NO 3 − ions, but after sublimation it consists of molecules with the covalent structure O 2 N-O-NO 2 in the gaseous phase. The molecular structure is retained for several hours in the solid state after rapid cooling of the gas on a surface at -180°C. Over time or on warming to -80°C the covalent structure O 2 N-O-NO 2 reverts to the ionic structure (NO 2 + : NO 3 − ) [3]. The first detailed investigation of the vibrational structure and the molecular structure of N 2 O 5 was carried out more than 40 years ago [4] and was based on the assumption that the N 2 O 5 molecule has a planar structure with C 2v symmetry.In agreement with the structural data [5] the double bonds between the four oxygen atoms and the two nitrogen atoms in N 2 O 5 were equal to 0.1188 nm, and the bonds between the oxygen atom at the center of the molecule and the nitrogen atoms were equal to 0.1498 nm. The angle between the central oxygen atom and the nitrogen atoms was equal to 111.8°and the angle between the nitrogen atoms and the outer oxygen atoms was equal to 133.2°. The authors of [5] concluded that the energy of the molecular structure of N 2 O 5 was minimal when the two torsional angles of rotation t 1 = t 2 » 30°(structure with symmetry C 2 , see Fig. 1c). Subsequent quantum-chemical study [6] showed that the planar configuration of the molecule was unstable and the structure with symmetry C 2 had the greatest energetic stability. 660040-5760/07/4301-0066

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Quantum-chemical DFT calculations of the molecular structure of N2O5 in the gas and solid phases

et al. 2007

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“…The calculated structural parameters are compared with results of electron diffraction study 5 in Fig. 1.…”

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confidence: 99%

“…The largest deviation between the calculated and electron diffraction bond angles is found for the N-O-N angle for which the experimental result is associated with a larger than usual uncertainty. 5 The calculated vibrational frequencies and IR intensities are compared with the latest matrix IR results of Bencivenni et al 1 in Table I. Note that in this table the observed frequencies were assigned on the basis of the calculated results which are in agreement with the DFT results of Stirling et al 3 All the experimental and theoretical studies are in agreement in the assignment of the NO 2 stretching fundamentals ͑ 1 , 2 , 9 , and 10 ͒, but there are some controversies on the assignments of the rest of the fundamentals.…”

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confidence: 99%

Comment on ‘‘Infrared spectrum and theoretical study of the dinitrogen pentoxide molecule (N2O5) in solid argon’’ [J. Chem. Phys. 104, 7836 (1996)]

Zhun

Zhou

Liu

1996

The Journal of Chemical Physics

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Density functional theory using B3LYP functional predicts the structural and IR spectral features of N2O5 accurately. The disagreement between DFT and observed IR frequencies reported in a recent paper is due to incorrect vibrational assignment. Agreement between the calculated observed isotope shifts indicates that the major product of the reaction between NO2 and 18O3 is more likely NO2–O–NO18O instead of NO2–18O–NO2.

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“…The interatomic distances for each conformer resulting from inclusion of these differences were of a type symbolized by r a and required corrections for the effects of vibrational averaging. We used the previously calculated [1] corrections, interpolating as necessary. The Boltzmann weight of each conformation was derived from the torsional potential defined by Eqn.…”

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A Reinvestigation of the Structure and Torsional Potential of N2O5 by Gas-Phase Electron Diffraction Augmented byAb Initio Theoretical Calculations

McClelland

Richardson

Hedberg

2001

HCA

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Dedicated to Professor Edgar Heilbronner on the occasion of his 80th birthday. K. H. recalls with great pleasure both the stimulating scientific collaboration and the many enjoyable social occasions that took place over 50 years ago.Gaseous N 2 O 5 consists of two NO 2 groups bonded to a bridging O-atom to form a nonlinear NÀOÀN moiety. The NO 2 groups undergo slightly hindered internal rotation around the bonds to the bridge so that instantaneous composition of the gaseous system is characterized by molecules with all combinations of torsion angles. In an earlier investigation, an attempt was made to determine the coefficients for an empirical form of the double-rotor torsional potential, and the bond lengths and bond angles measured subject to assumptions that the structure of the OÀNO 2 groups was invariant to torsion angle and that these groups had C 2v symmetry. The system has now been reinvestigated in terms of a more realistic model in which this symmetry restriction was relaxed, account was taken of structural changes in the NO 2 groups with torsion angle as predicted by ab initio theory at the B3LYP/6-311 G* level, and a more convenient form of the torsional potential was assumed. The most stable conformation has C 2 symmetry with torsion angles t 1 (defined as a(NÀOÀNO 4 )) equal to t 2 (defined as a(NÀOÀNO 6 )) equal to 33.78; because of the broad potential minimum in this region, the uncertainty in these angles is difficult to estimate, but is probably 3 ± 48. The results for the bond lengths and bond angles for the most stable conformation are r g (NÀO) 1.505(4) , r g (NO) 1.188(2) , a a (NÀOÀN) 112.3(17)8, a a (ONO) 134.2(4)8, ha a (OÀNO)i 112.8(2)8. The difference between the symmetry-nonequivalent OÀNO angles is estimated to be ca. 6.78 with the larger angle positioning the two NO bonds on different NO 2 groups nearest each other. These average values are similar to those obtained in the original study. The main difference is found in the shape of the torsional potential, which at t 1 /t 2 0/0 has a saddle point in the present work and a substantial peak in the earlier. The implication of the torsion-angle findings for electron-diffraction investigations of this type is discussed.Introduction. ± In a previous report [1], we described the results of a gas-phase electron-diffraction (GED) study of molecular N 2 O 5 . This work confirmed that the molecule consisted of two NO 2 groups linked by a bridging O-atom (O 2 NÀOÀNO 2 ), and that the NÀOÀN moiety was nonlinear (Fig. 1). It also confirmed that the NO 2 groups were undergoing large amplitude motion, perhaps more accurately described as restricted internal rotation, about the bonds connecting them to the apical O-atom. The problem thus divided itself into two parts: the short-range structure of the molecule determined by the bond lengths and bond angles, and the long-range structure determined by the torsion angles of the two rotating groups, themselves dependent on the nature of the potential surface V(t 1 ,t 2 ). The analysis of the short-range...

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Molecular structure of dinitrogen pentoxide in the gas phase. Large amplitude motion in a system of coupled rotors

Cited by 49 publications

References 1 publication

Quantum-chemical DFT calculations of the molecular structure of N2O5 in the gas and solid phases

Quantum-chemical DFT calculations of the molecular structure of N2O5 in the gas and solid phases

Comment on ‘‘Infrared spectrum and theoretical study of the dinitrogen pentoxide molecule (N2O5) in solid argon’’ [J. Chem. Phys. 104, 7836 (1996)]

A Reinvestigation of the Structure and Torsional Potential of N2O5 by Gas-Phase Electron Diffraction Augmented byAb Initio Theoretical Calculations

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