Nonempirical valence bond studies of the origin of the rotation barrier for nitrogen oxide (N2O4)

Harcourt, Richard D.; Skrezenek, Frances L.

doi:10.1021/j100381a018

Cited by 22 publications

(6 citation statements)

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“…But a number of studies [33][34][35][36] have presented evidence that -bonding interactions between cis O atoms play a more important role than interactions. In the case of N 2 O 4 , it has been suggested 32 that the N-N -bonding interaction is primarily responsible for the stability of the planar structure.…”

Section: The Origin Of the Torsional Barriermentioning

confidence: 99%

Ab initio study of the torsional potential energy surfaces of N2O3 and N2O4: Origin of the torsional barriers

Halpern

Glendening

2007

The Journal of Chemical Physics

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Intrinsic reaction coordinate (IRC) torsional potentials were calculated for N(2)O(4) and N(2)O(3) based on optimized B3LYP/aug-cc-pVDZ geometries of the respective 90 degrees -twisted saddle points. These potentials were refined by obtaining CCSD(T)aug-cc-pVXZ energies [in the complete basis set (CBS) limit] of points along the IRC. A comparison is made between these ab initio potentials and an analytical form based on a two-term cosine expansion in terms of the N-N dihedral angle. The shapes of these two potential curves are in close agreement. The torsional barriers in N(2)O(4) and N(2)O(3) obtained from the CCSD(T)/CBS//B3LYP/aug-cc-pVDZ calculations are 2333 and 1704 cm(-1), respectively. For N(2)O(4) the torsion fundamental frequency from the IRC potential is 87.06 cm(-1), which is in good agreement with the experimentally reported value of 81.73 cm(-1). However, in the case of N(2)O(3) the torsional frequency found from the IRC potential, 144 cm(-1), is considerably larger than the reported experimental values 63-76 cm(-1). Consistent with this discrepancy, the torsional barrier obtained from several different calculations, 1417-1718 cm(-1), is higher than the value of 350 cm(-1) deduced from experimental studies. It is suggested that the assignment of the torsional mode in N(2)O(3) should be reexamined. N(2)O(4) and N(2)O(3) exhibit strong hyperconjugative interactions of in-plane O lone pairs with the central N-N sigma* antibond. Hyperconjugative stabilization is somewhat stronger at the planar geometries because 1,4 interactions of lone pairs on cis O atoms promote delocalization of electrons into the N-N antibond. Calculations therefore suggest that the torsional barriers in these molecules arise principally from a combination of 1,4 interactions and hyperconjugation.

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Section: The Origin Of the Torsional Barriermentioning

confidence: 99%

Ab initio study of the torsional potential energy surfaces of N2O3 and N2O4: Origin of the torsional barriers

Halpern

Glendening

2007

The Journal of Chemical Physics

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“…ASideal mixture = --R(nsolut~ln Xsolute "[-n~ol~,,tln X~ol~,~t) 9 (20) In Eq. We may conclude that the entropies of solution of both N204 and NO 2 in the corresponding solvents are quite similar.…”

Section: Entropy Of Solution Of Nomentioning

confidence: 99%

“…The experimental N-N distance is 0.1756 nm, a value obtained by both a neutron diffraction study and a rotational analysis of spectroscopic constants [17,18]. Infrared studies and nonempirical valence bond studies were done in order to provide information on the barrier to intemal rotation [19,20].…”

Section: Introductionmentioning

confidence: 99%

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Dissociation equilibrium of dinitrogen tetroxide in organic solvents: An electron paramagnetic resonance measurement

Mendiara

Perissinotti

2003

Appl. Magn. Reson.

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The dissociation equilibrium of N204-NO 2 has been measured in hexane, carbon tetrachloride and chloroform at different temperatures. The equilibrium constants at 298.15 K (25~ K,, (molality basis), are 3.5.10 -~ in hexane, 5.9-10 -6 in carbon tetrachloride and 5.3 9 l0 -6 in chloroform. The EPR technique has been used to quantify the NO_, radical. These data are compared with gas-phase and solution data of previous reports. The applicability of Hildebrand and Scatchard theory of solutions is also discussed and some thermodynamic properties are deduced, such as Henry's N204 and NO 2 constants in different solvents.

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“…It is well known that the N-N bond lengths in N,O, [19,20] studies on N204 indicate that the planarity arises from the existence of long-range bonding overlap or cis-0-0 overlap, and simultaneously there is no N-N T bonding. This conclusion may also be extended to explain why the cis-isomer is more stable than the transisomer of N,O,.…”

Section: Introduction Lthough Nowadays Molecular Orbital (Mo)mentioning

confidence: 99%

Why N₂O₂ is cis while (CHO)2 is trans: MO and VBstudies

Zhang

1995

Int J of Quantum Chemistry

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=The nonempirical valence-bond method as well as the molecular orbital method are applied to investigate the structures of N,O, and (CHO),. Results show that in either molecule the u-component tends toward a trans conformation, whereas, the +component tends toward a cis conformation. Moreover, even if there are some long-range bonding overlaps in the cis structure, the bonding energy cannot counteract the increased Coulombic repulsive energy compared with the trans structure. In other words, for a cis conformation, there is a competition between the Coulombic destabilization and the 71 electronic stabilization. The latter is more preferable to a cis conformation of N202, while the Coulombic repulsive interaction should be responsible for the trans conformation of (CHO),. The nonempirical VB calculations show that the w delocalization energy in N,O, is negligible, while the value in (CHO), is about 4.5 kcal/mol. 0 1995 John

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Nonempirical valence bond studies of the origin of the rotation barrier for nitrogen oxide (N2O4)

Cited by 22 publications

References 2 publications

Ab initio study of the torsional potential energy surfaces of N2O3 and N2O4: Origin of the torsional barriers

Ab initio study of the torsional potential energy surfaces of N2O3 and N2O4: Origin of the torsional barriers

Dissociation equilibrium of dinitrogen tetroxide in organic solvents: An electron paramagnetic resonance measurement

Why N₂O₂ is cis while (CHO)2 is trans: MO and VBstudies

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Nonempirical valence bond studies of the origin of the rotation barrier for nitrogen oxide (N2O4)

Cited by 22 publications

References 2 publications

Ab initio study of the torsional potential energy surfaces of N2O3 and N2O4: Origin of the torsional barriers

Ab initio study of the torsional potential energy surfaces of N2O3 and N2O4: Origin of the torsional barriers

Dissociation equilibrium of dinitrogen tetroxide in organic solvents: An electron paramagnetic resonance measurement

Why N2O2 is cis while (CHO)2 is trans: MO and VBstudies

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Why N₂O₂ is cis while (CHO)2 is trans: MO and VBstudies