Molecular mechanics (MM2 and MM3) calculations on aliphatic and aromatic nitro compounds

Allinger, Norman L.; Kuang, J.; Thomas, H. D.

doi:10.1016/0166-1280(90)85051-n

Cited by 29 publications

(15 citation statements)

References 23 publications

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“…Observed bond dissociation energies (BDE) for the bond in CH 3 NO 2 range from 58 -60 kcal/mol C 9 N [57], in good agreement with the BAC-MP4 value of 58.9 kcal/mol [23 -25] [35,59,60]. The deviations in the entropy S 0,298 reported for CH 3 NO 2 are unusually large, ranging from 65.7 [35] to 72.0 cal/(mol K) [34].…”

Section: IImentioning

confidence: 83%

Nitromethane dissociation: Implications for the CH3 + NO2 reaction

Glarborg¹,

Bendtsen²,

Miller³

1999

Int. J. Chem. Kinet.

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The thermal decomposition of nitromethane under highly diluted conditions in shock tubes has been analyzed in terms of a detailed chemical kinetic model. The experimental data were adopted from Glä nzer and Troe, Hsu and Lin, and Zhang and Bauer, respectively; they cover the temperature range and pressures from 0.5 to 6.0 bar. Based on 1000-1400 K these results, rate constants for the reactions (R1) andThe high and low pressure limits for reaction (R1) determined by Glä nzer and Troe have been shown to be consistent with more recent shock tube data, provided a center broadening parameter is introduced to describe the fall-off behavior. Our reinterpretation of the shock tube results of Glä nzer and Troe together with room temperature measurements indicate that the rate constant for (R14) decreases slightly with temperature, as cm mol s . order of magnitude faster than recombination of CH 3 and NO 2 to form nitromethane. Based on the available data for the forward and reverse rate of reaction (R1) a value of 66.7 Ϯ 2.0 cal/(mol K) for the entropy S 0,298 of CH 3 NO 2 is estimated.

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Section: IImentioning

confidence: 83%

Nitromethane dissociation: Implications for the CH3 + NO2 reaction

Glarborg¹,

Bendtsen²,

Miller³

1999

Int. J. Chem. Kinet.

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“…Because the V 2 torsional potential is also a function of the 7r index pO of the hinge bond, we also had to modify the values given by Allinger et al [17] as they are relative to compounds treated as nonconjugate. The concerned dihedrals here are 2-2-46-7, 37-2-46-7, and 40-2-46-7.…”

Section: Molecular Mechanicsmentioning

confidence: 99%

“…In the 1987 MM2 version the nitro group is not present. In the 1991 version, it is assumed to be linked to a nonconjugate system [ 17]. We thus modified the MM2 program so that the nitrogen atom of the NOz group (atom type 46) could be included in the 7r system.…”

Section: Molecular Mechanicsmentioning

confidence: 99%

Molecular structure of 2-Amino-5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazol (Megazol) and related compounds: A concerted study using X-ray crystallography, molecular mechanics, and semiempirical methods

Rameau

Devillers

Declercq³

et al. 1996

Struct Chem

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A structural study of three nitroimidazoles was carried out using molecular mechanics, semiempirical methods, and X-ray crystallography. Structural features which might account for the high efficiency of 1 (Megazol) as an antiparasitic drug and its opposite, the inactivity of its regiomers 2 and 3 were examined, i.e., coplanarity of the two rings, preferred conformations, and rotational barriers around the pivot bond between the two rings. For the three compounds an antiperiplanar conformation is preferred for the N(CH3) and C--S bonds. For compounds 1 and 3, the rings are coplanar, with 2 being somewhat twisted. The geometry obtained by molecular mechanics for compound 1 is in excellent agreement with the X-ray structure, and greater confidence can be placed in this method than in semiempirical ones. Similarities observed on the LUMO positions, as well as rotational barriers lead to the conclusion that the differences in biological activity of these compounds do not rely on their ground state properties but rather on their subsequent reactions with oxygen. In addition, the calculations revealed significant structural information of a family of biological importance (nitroimidazoles) and constitute a comparative test for the MM2, AMI, and PM3 methods.

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“…Instead of trying to revise the MM2 force field, a new force field (called MM3) 1 was instead developed. 3 The MM3 force field has been applied to a variety of compounds including hydrocarbons, 3 alkenes, 4 alcohols and ethers, 5 aldehydes and ketones, 6 amines, 7 conjugated alkenes, 8 nitro compounds, 9 sulfides, 10 disulfides 11 and conjugated carbonyls. 12 In this paper, we are concerned with the extension of MM3 force field to deal with the organogermanes.…”

Section: Introductionmentioning

confidence: 99%