An ab initio calculation of the structure and scaled quantum mechanical harmonic force field of nitromethane

Bock, Charles W.; Krasnoshchiokov, S.V.; Khristenko, L. V.; Panchenko, Yu. N.; Pentin, Yu. A.

doi:10.1016/0166-1280(87)87022-7

Cited by 16 publications

(11 citation statements)

References 27 publications

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“…1 Thus, the IR spectra 1 was preferred for the sake of compatibility with the other species (nitro-methylradical,deuterated-nitromethane, nitro-ethane,nitro-propane,nitrobutane, and nitro-benzene). The Melius 2 vibrations compare 11 very well with those of Bock et al, 10 of McKean and Watt, 9 and the IR spectrum. 1 However Melius lists spin = 1 (when it should be zero), and S 2 = 0.30, which suggests spin contamination.…”

Section: Nitro-methane Ch 3 Nosupporting

confidence: 58%

“…10 The MOPAC calculations resulted in transition/inversion states as seen from the vibrational results of PM3 (one imaginary vibration). 11 Therefore, the calculated heats of formation are not listed.…”

Section: Nitro-methane Ch 3 Nomentioning

confidence: 95%

“…The vibrationalspectrumwas calculatedby Bock et al, 10 using ab initio methods at HF/631G ¤ levels and compared with experimental data. MOPAC calculations for PM3 and PM3/UHF have resulted in transition state species only.…”

Section: Deuterated Nitro-methane CD 3 Nomentioning

confidence: 99%

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Ideal Gas Thermodynamic Properties of Propellants and Explosive Compounds

Burcat

2000

Journal of Propulsion and Power

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The detailed ideal gas thermodynamic properties of 29 nitro and nitrate compounds are calculated together with two of their radicals. Most of these compounds are high explosives: TNT, RDX, HMX, PETN, NPN, and NG, whereas others serve as propellants or specialty fuels such as nitromethane. The thermodynamic properties were calculated from fundamental molecular data. The molecular data were gathered from the literature or calculated for this purpose. The enthalpy of formation of 1-nitro-pentane is estimated to be ¡ 39.3 § 0.5 kcal/mole, and that of 1-nitro-hexane is ¡ 44.3 § 0.7 kcal/mole. Nomenclature A, B, C= spectroscopic rotational constants of a molecule, cm ¡ 1 C p = heat content function, cal/mole K H 0 T = absolute enthalpy, kcal/mole IA, IB, IC = moments of inertia of a molecule, g cm 2 £ 10 ¡ 39 Ia, Ib, Ic = moments of inertia of a molecule, g cm 2 £ 10 ¡ 39 Ir = internal moment of rotation, g cm 2 £ 10 ¡ 39 Ired = reduced internal moment of rotation, g cm 2 £ 10 ¡ 39 n = stoichiometric factor S T = entropy, cal/mole K V ( R) = internal rotation barrier, kcal/mole D H f (T ) = enthalpy of formation at temperature T , kcal/mole m = fundamental vibration in a molecule, cm ¡ 1 r = SYMNO, external symmetry of a molecule

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Section: Nitro-methane Ch 3 Nosupporting

confidence: 58%

Section: Nitro-methane Ch 3 Nomentioning

confidence: 95%

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Ideal Gas Thermodynamic Properties of Propellants and Explosive Compounds

Burcat

2000

Journal of Propulsion and Power

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“…Both techniques indicate that C H 3 N 0 2 has staggered conformation. Previous a b initio calculations on the staggered and eclipsed conformers of nitromethane were carried out at the S C F level (17,18) and a slight preference (lower than 0.1 kJ/mol) was found for the staggered orientation at the MP2/6-3 lG*//HF/6-3 lG* level (1 8). T o recalculate the equilibrium geometry of CH,NO,, the eclipsed and staggered conformations were optimized at the HF/6-31G** and MP2/6-3 l G * levels.…”

Section: Molecular Structuresmentioning

confidence: 99%

Abinitio study on radical anions of nitro compounds

Ramondo¹

1992

Can. J. Chem.

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This paper is dedirnted to Professor Sigeru Huzinaga on the occasion of his 65th birthdayFABIO RAMONDO. Can. J. Chem. 70, 3 14 (1992).The results of ab itritio molecular orbital calculations on some nitro compounds, RN02 (R = CH,, CF,, CH,F, BH,, BF,, BHF, C6H5) and on the corresponding radical anions are reported. The geometries of the neutral and charged species were optimized at the SCF and MP2 levels of theory employing the 6-31G* and the 6-3 1 +G* basis sets. The rotation about the CN and BN bonds reveals distinct conformations for each molecule and vibrational frequencies were determined for such structures. All the employed levels of theory predict structural differences between neutral and charged molecules. The major geometrical changes occurring by electron adding to R N 0 2 consist in the lengthening of the NO bonds and in the shortening of the CN and BN bonds. The radical anions are calculated to be pyramidal at nitrogen in the stable conformers of CH,NO,-, CF3N02-, CH,FNO,-, while, for the T-electron-accepting substituents (BH,, BHF, BF,, C6H5), the anion is planar. Electron correlation energy corrections in the framework of Moiler-Plesset perturbation theory were included to determine relative stabilities between different conformations. At the MP4/6-3 1G*//MP2/ 6-31G* level, an easy rotation of the NO, group is predicted for all the radical anions and neutral molecules with the exception of BH?NO,-, BF2N02-, and BHFN0,-, which show high torsional barriers about the BN bond.

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“…The results of an ab initio calculation has been presented by Bock et al 14 With a split valence 6-31G and polarization 6-31G*͑5D͒ basis sets they find r values of 1.7°and 0.4°, respectively, for the staggered configuration, but no information as to the sign can be found. Their x value seems to be extremely small, whereas they find a positive dy .…”

Section: Relaxations In Nitromethanementioning

confidence: 99%

Structural relaxation in nitromethanelike molecules

rensen

1996

The Journal of Chemical Physics

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In a molecule with a large-amplitude coordinate like the internal rotation angle of the methyl hydrogens relative to the CNO 2 fragment in nitromethane the other structural parameters are not strictly constant, but vary slightly with the angle. This behavior is usually described by saying that relaxations of the vibrational coordinates take place, and it is observed by the presence of special terms in the Hamiltonian needed in fitting the spectra. It is shown how relaxations can be treated theoretically by a perturbation method. Subsequent quantitative analysis of the effects in nitromethane indicates that the dominant relaxations involve the rocking and wagging coordinates of the nitro group. The maximum rocking relaxation in the staggered configuration is found to be r Ϸ4°, whereas the maximum wagging relaxation in the eclipsed configuration is smaller, w Ϸ0.7°.

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An ab initio calculation of the structure and scaled quantum mechanical harmonic force field of nitromethane

Cited by 16 publications

References 27 publications

Ideal Gas Thermodynamic Properties of Propellants and Explosive Compounds

Ideal Gas Thermodynamic Properties of Propellants and Explosive Compounds

Abinitio study on radical anions of nitro compounds

Structural relaxation in nitromethanelike molecules

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