Microwave Spectra, Dipole Moment, and Barrier to Internal Rotation of CH3NO2 and CD3NO2

Tannenbaum, Eileen; Myers, Rollie J.; Gwinn, William D.

doi:10.1063/1.1742845

Cited by 202 publications

(50 citation statements)

References 15 publications

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“…As illustrated in Fig. 5 the torsional potential has a two-fold symmetry in contrast to the six-fold symmetry of the torsional potential of CH3-NO2 which has a calculated barrier of 0.026 kcal/mol, consistent with the experimentally observed low barrier to rotation (0.006 kcal/mol) (9). This rotational barrier in CH3-NO2 corresponds to a typical low value that is characteristic to sixfold barriers.…”

Section: Conformation Of -:Ch2-no2supporting

confidence: 58%

A theoretical study on the stereochemistry and protonation of ⁻:CH₂—NO₂

Mezey¹,

Kresge²,

Csizmadia³

1976

Can. J. Chem.

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The molecular conformation of −:CH2NO2 is found to be planar with an extremely shallow potential curve to pyramidal inversion. This suggests that suitable substituents could conceivably perturb the System into a pyramidal configuration corresponding to double minimum on the potential surface and that a chiral carbanion might therefore exist. Rotating the NO2 group out of planarity by 90° raises the barrier to inversion at carbon by an appreciable amount.A Mulliken population analysis gives a charge distribution in which a substantial portion of the negative charge has shifted from carbon to oxygen; this is consistent with the well-known tendency of nitronate ions to undergo simultaneous competitive protonation on carbon and oxygen.

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Section: Conformation Of -:Ch2-no2supporting

confidence: 58%

A theoretical study on the stereochemistry and protonation of ⁻:CH₂—NO₂

Mezey¹,

Kresge²,

Csizmadia³

1976

Can. J. Chem.

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“…If the fornlation of this new barrier to internal rotation is combined ~vith the postulate made by Leffek el al. ( 5 ) that the barrier to rotation of CI-I3 groups is slightly higher than that of CD3 groups, which, although not predicted by theory, is supported by a limited amount of experimental evidence (21,22), the entropy of activation for the protium compound will be a larger negative quantity than that for the deuterium compound. Thus, (ASD* -ASH*) will be positive.…”

Section: Resul'i's X S D Disccssioxmentioning

confidence: 83%

SECONDARY KINETIC ISOTOPE EFFECTS IN BIMOLECULAR NUCLEOPHILIC SUBSTITUTIONS: II. Α-Deuterium EFFECTS IN MENSCHUTKIN REACTIONS OF METHYL IODIDE

Leffek¹,

MacLean²

1965

Can. J. Chem.

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Secondary deuterium isotope elTects have been measured for the reactions between methy1 and methyl-da iodides and a series of tertiary amines in benzene solvent. Deuteriuin substitution increased the rate of each reaction but the rate ratios ( k~/ k~) show no systematic change with variation in the structure of the amine. The isotope elfect for the reaction with 2-picoline was measured a t different telnperatures over a range of 40 deg and shows no change. These isotope effects may be rationalized a s internal rotational effects of the methyl group or a s solvation erects.h h n y of the kinetic secondary deuterium isotope effects recorded in the literature have been nleasured in reaction systenls in which solvation of the reaction site is a n important, but relatively unlinown, factor. For such systems it is very difficult to assess what part of the isotopic rate change is due to solvation phenomena and what part colues about as a result of internal changes in the reacting molecule. Investigations of the dependence of secondary isotope effect on solvent composition give no clear answer to this problem. Shiner and Verbanic (1) found that isotope effects produced by a-deuteration of the alkyl group in p-alkyl benzhydryl chlorides solvolyzillg in aqueous acetone were marlcedly dependent on the water content of the solvent, although the isotopic rate ratios were all quite close to unity. For a-deuterated methyl and ethyl p-bromobenzenesulfonates, Lewis and co-~vorlrers (2) found only very small changes in the isotope effect between the two solvents, methanol and acetic acid, ~v h i c l~ they interpreted on the basis of a difference in mechanism of reaction rather than a direct solvation difference. Similar changes in isotope effect, presumably due to mechanism changes, were observed by Lewis and Boozer (3) in the solvolysis reactions of 2-pentyl-1,1,1,3,3,dj-p-toluenesulfonate in acetic acid, formic acid, and 80% aqueous ethanol. Similar results were observed by Winstein and Talrahashi (4) for 3-methyl-2-butyl-3d-9-toluenesulfonate solvolyzing in the same solvents.Thus changing the solvent gives information concerning solvation isotope effects which is not separable fro111 information concerning effects resulting from changes in mechanism. Apart from the deuterated p-allryl benzhydryl chlorides, there is no clear change of isotope effect with solvent for which there is not a t least the possibility of a mechanistic change.Recently, Leffelr, Robertson, and Sugamori (5) proposed that the @-deuteriuln isotope effects in the water solvolyses of isopropyl compounds, which are rate changes brought about by changes in the entropy of activation, were due to differences in the barriers to rotation of the methyl and 111ethyl-d3 groups and differences in these barriers between the initial arid transition states of the reaction. Although a reasonably large part of the observed effect could be accounted for on this theory, the uniinportance of solv a t' ion a s the source of the effect was not proved. I-Ialevi and co-wor...

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“…It consists of a heavy planar frame NO 2 with local symmetry C 2V and a lighter top CD 3 which has C 3V local symmetry. The detailed microwave, IR and Raman study of Nitromethane and its deuterated derivatives in all the three phases were performed by many workers [1][2][3][4][5][6][7]. The microwave analysis of nitromethane-D 3 was reinvestigated by Sorensen et al [8] to understand the interaction between almost free internal rotation and vibration.…”

Section: Introductionmentioning

confidence: 99%

DFT molecular structure and initial assignment for the FTIR spectrum of ν7 band of nitromethane-D3

Pal

Kshirsagar

2010

Indian J Phys

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The preliminary analysis of the DFT calculations and the high-resolution Fourier transform spectrum of the Q 7 band of CD 3 NO 2 have been carried out for the first time. The rotational structure up to J = 10 have been fitted using Watson's A-reduction in I r representation with a standard deviation of 0.0048cm -1 . The rotational constants A, B, C have been obtained for the Q 7 state of CD 3 NO 2 with good statistical significance.

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Microwave Spectra, Dipole Moment, and Barrier to Internal Rotation of CH3NO2 and CD3NO2

Cited by 202 publications

References 15 publications

A theoretical study on the stereochemistry and protonation of ⁻:CH₂—NO₂

A theoretical study on the stereochemistry and protonation of ⁻:CH₂—NO₂

SECONDARY KINETIC ISOTOPE EFFECTS IN BIMOLECULAR NUCLEOPHILIC SUBSTITUTIONS: II. Α-Deuterium EFFECTS IN MENSCHUTKIN REACTIONS OF METHYL IODIDE

DFT molecular structure and initial assignment for the FTIR spectrum of ν7 band of nitromethane-D3

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Microwave Spectra, Dipole Moment, and Barrier to Internal Rotation of CH3NO2 and CD3NO2

Cited by 202 publications

References 15 publications

A theoretical study on the stereochemistry and protonation of −:CH2—NO2

A theoretical study on the stereochemistry and protonation of −:CH2—NO2

SECONDARY KINETIC ISOTOPE EFFECTS IN BIMOLECULAR NUCLEOPHILIC SUBSTITUTIONS: II. Α-Deuterium EFFECTS IN MENSCHUTKIN REACTIONS OF METHYL IODIDE

DFT molecular structure and initial assignment for the FTIR spectrum of ν7 band of nitromethane-D3

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A theoretical study on the stereochemistry and protonation of ⁻:CH₂—NO₂

A theoretical study on the stereochemistry and protonation of ⁻:CH₂—NO₂