Ab initio and DFT conformational study on nitrosamine (H2N–N=O) and N-Nitrosodimethylamine [(CH3)2N–N=O]

Monte, Silmar A. do; Ventura, Elizete; Costa, Tamires Ferreira da; Santana, Sidney R.

doi:10.1007/s11224-010-9721-8

Cited by 9 publications

(7 citation statements)

References 37 publications

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“…Thus, the protonated (on the N amino) methylated nitrosamine is much less loosely bound than the corresponding smaller (nonmethylated) nitrosamine. A similar effect has been obtained for the corresponding nonprotonated systems …”

Section: Resultssupporting

confidence: 83%

Effect of methylation on relative energies of tautomers and on the intramolecular proton transfer barriers of protonated nitrosamine: A MR‐CISD study

et al. 2015

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MR-CISD, MR-CISD+Q, and MR-AQCC calculations have been performed on the minima and transition states (corresponding to intramolecular proton transfer between the protonation sites) of the ground state of protonated nitrosamine and N,N-dimethylnitrosamine. Our highest level results (MR-AQCC/cc-pVTZ) for the smaller system indicate that protonation on the N amino (2a) is practically as favorable as the most favorable protonation on the O atom (1a). They also suggest that protonation on the nitroso N atom (2c) is ∼14.5 kcal/mol less favorable than 1a. Results obtained at the MR-CISD+Q/cc-pVTZ level indicate that the effect of methylation on the relative energies of the tautomers is, in order of importance, 2a > 2c and increases their energies by ∼17.5 and 4.8 kcal/mol, respectively. They also indicate that methylation alters significantly the intramolecular proton transfer barriers. The largest differences between the common geometric parameters of both systems have been found for 2a.

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Section: Resultssupporting

confidence: 83%

Effect of methylation on relative energies of tautomers and on the intramolecular proton transfer barriers of protonated nitrosamine: A MR‐CISD study

et al. 2015

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“…Structures 3 and 3 ′ are enantiomers. In 1 , the C=N bond length was calculated to be 1.27 Å and the N–N bond length was 1.36 Å, and the amino group is pyramidal in accord with previous calculations . Upon formation of the O–C bond (1.46 Å) in 2 , the C=N bond lengthens to 1.42 Å.…”

Section: Resultssupporting

confidence: 81%

Theoretical Study of the Reaction Formalhydrazone with Singlet Oxygen. Fragmentation of the C=N Bond, Ene Reaction and Other Processes

Rudshteyn

Castillo

Ghogare

et al. 2013

Photochem & Photobiology

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Photobiologic and synthetic versatility of hydrazones has not yet been established with 1O2 as a route to commonly encountered nitrosamines. Thus, to determine whether the “parent” reaction of formalhydrazone and 1O2 leads to facile C=N bond cleavage and resulting nitrosamine formation, we have carried out CCSD(T)//DFT calculations and analyzed the energetics of the oxidation pathways. A [2 + 2] pathway occurs via diradicals and formation of 3-amino-1,2,3-dioxazetidine in a 16 kcal/mol process. Reversible addition or physical quenching of 1O2 occurs either on the formalhydrazone carbon for triplet diradicals at 2–3 kcal/mol, or on the nitrogen (N(3)) atom forming zwitterions at ~15 kcal/mol, although the quenching channel by charge-transfer interaction was not computed. The computations also predict a facile conversion of formalhydrazone and 1O2 to hydroperoxymethyl diazene in a low-barrier ‘ene’ process, but no 2-amino-oxaziridine-O-oxide (perepoxide-like) intermediate was found. A Benson-like analysis (group increment calculations) on the closed shell species are in accord with the quantum chemical results.

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“…Preliminary calculations with the neutral DMNA molecule show that either the N or O atom of NO group can form hydrogen bond with one water molecule, which also supports the H bond donation to the O atom of structures shown in Figure . Conversely, the N amino atom does not form any hydrogen bond, probably due to a significant contribution of a dipolar resonance structure with a partial positive charge on this atom …”

Section: Resultsmentioning

confidence: 99%

Solvent effect on the tautomers' stabilities of protonated N,N‐dimethylnitrosamine: The role of hydrogen bonds network

Andrade

Ventura

Monte

2016

Int J of Quantum Chemistry

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DFT calculations have been applied in order to study the free energies of the structures corresponding to the three different protonation sites of N,N‐dimethylnitrosamine (DMNA). The solvent effect has been taken into account through the study of clusters consisting of protonated DMNA and up to four explicit water molecules, either in the absence or in the presence of a continuum (CPCM) solvation model. Addition of water molecules has been done by a careful screening procedure through which all important hydrogen bonds are likely to be considered. Protonation of DMNA makes all their lone pairs no longer available for hydrogen bond formation with water molecules, such that hydrogen bonds have been observed, for almost all structures, only between water molecules and between one water molecule and the protonated DMNA, in this latter case intermediated by the proton. The stabilities of the solvated structures are governed not only by the number of hydrogen bonds but also by the positions of the water molecules involved in these bonds, as well as by which of them donate or accept H atoms. Our results indicate that oxygen protonation is the most favorable one, regardless of the presence of water molecules. In vacuum protonation at the N‐amino (2a) is approximately as favorable as protonation at the N nitroso (2c). However, in water the former protonation is by far the less favorable one. Our best estimates for the ΔG values in bulk solvent are: ΔG(2a) ≈ 17.9, ΔG(1c) ≈ 4.3, and ΔG(2c) ≈ 4.9 kcal/mol.

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Ab initio and DFT conformational study on nitrosamine (H2N–N=O) and N-Nitrosodimethylamine [(CH3)2N–N=O]

Cited by 9 publications

References 37 publications

Effect of methylation on relative energies of tautomers and on the intramolecular proton transfer barriers of protonated nitrosamine: A MR‐CISD study

Effect of methylation on relative energies of tautomers and on the intramolecular proton transfer barriers of protonated nitrosamine: A MR‐CISD study

Theoretical Study of the Reaction Formalhydrazone with Singlet Oxygen. Fragmentation of the C=N Bond, Ene Reaction and Other Processes

Solvent effect on the tautomers' stabilities of protonated N,N‐dimethylnitrosamine: The role of hydrogen bonds network

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