Effect of Substituents on the Strength of N–X (X = H, F, and Cl) Bond Dissociation Energies: A High-Level Quantum Chemical Study

O'Reilly, Robert J.; Karton, Amir; Radom, Leo

doi:10.1021/jp203108e

Cited by 33 publications

(19 citation statements)

References 70 publications

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“…Finally, it is of interest to point out that although N ‐chloropyrrole has been isolated and studied, N ‐bromopyrrole remains elusive. It seems plausible that the particularly low NBr BDE of N ‐bromopyrrole (162.2 kJ mol −1 ) would render the production of this compound a significant challenge, especially given that the NCl bond of N ‐chloropyrrole is substantially stronger (203.7 kJ mol −1 ) . However, it should be noted that even 2‐ and 3‐bromopyrrole, species that contain stronger CBr bonds, are also known to possess very limited stability …”

Section: Resultsmentioning

confidence: 99%

A dataset of highly accurate homolytic NBr bond dissociation energies obtained by Means of W2 theory

O'Reilly

Karton

2015

Int J of Quantum Chemistry

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Homolytic NBr bond dissociation constitutes the initial step of numerous reactions involving N‐brominated species. However, little is known about the strength of NBr bonds toward homolytic cleavage. We herein report accurate bond dissociation energies (BDEs) for a set of 18 molecules using the high‐level W2 thermochemical protocol. The BDEs (at 298 K) of the species in this set range from 162.2 kJ mol−1 (N‐bromopyrrole) to 260.6 kJ mol−1 ((CHO)2NBr). In order to compute BDEs of larger systems, for which W2 theory is not applicable, we have benchmarked a wide range of more economical theoretical procedures. Of these, G3‐B3 offers the best performance (root‐mean‐square deviations = 2.9 kJ mol−1), and using this method, we have computed NBr BDEs for four widely used N‐brominated compounds. These include (BDEs are given in parentheses): N‐bromosuccinimide (281.6), N‐bromoglutarimide (263.2), N‐bromophthalimide (274.7), and 1,3‐dibromo‐5,5‐dimethylhydantoin (218.2 and 264.8 kJ mol−1). © 2015 Wiley Periodicals, Inc.

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Section: Resultsmentioning

confidence: 99%

A dataset of highly accurate homolytic NBr bond dissociation energies obtained by Means of W2 theory

O'Reilly

Karton

2015

Int J of Quantum Chemistry

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“…Benchmark reference data have been taken from our previous study [7] and were obtained by means of W2w theory [8]. W2w represents a layered extrapolation to the relativistic, AE CCSD(T) basis-set limit and can achieve an accuracy in the kJ mol -1 range for molecules whose wave functions are dominated by dynamical correlation [54].…”

Section: W2w Reference Valuesmentioning

confidence: 99%

“…For example, if one uses nonrelativistic, vibrationless benchmark BDEs from W2w theory for the H 2 NAH and H 2 NACl bonds (483.6 and 274.4 kJ mol -1 , respectively) [7], then the MAD, LD, and NO for BDEs [7].…”

Section: Calculation Of Nah and Nacl Bdes Via Rsesmentioning

confidence: 99%

“…As far as we are aware, NACl bonds have not been the subject of a benchmark DFT evaluation study. We have recently carried out a systematic study [7] of the effect of substituents on NAX homolytic BDEs and RSEs by means of the high-level ab initio W2w thermochemical protocol [8] for a diverse set of 31 NAH and 31 NACl species. The chosen set included species of biological, synthetic, and industrial importance.…”

Section: Introductionmentioning

confidence: 99%

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NH and NCl homolytic bond dissociation energies and radical stabilization energies: An assessment of theoretical procedures through comparison with benchmark‐quality W2w data

O'Reilly¹,

Karton²,

Radom³

2011

Int J of Quantum Chemistry

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The performance of a large variety of contemporary density functional theory (DFT), double-hybrid DFT, and high-level Gaussian-n (Gn) procedures has been evaluated for the calculation of bond dissociation energies (BDEs) and radical stabilization energies (RSEs) associated with NAX bonds (X ¼ H, Cl). The chosen set of 62 NAX systems (31 NAH and 31 NACl) span a wide range of biologically relevant species. As reference values, we used benchmark-quality W2w data that we recently obtained as part of a systematic thermochemical study of substituent effects in these systems. Of the Gn schemes, the modified G4 procedures (G4-5H and G4(MP2)-6X) perform somewhat better than the corresponding standard G4 procedures for the NAX BDEs of these systems. For the NAH RSEs, G3X, G3X(MP2), G3X(MP2)-RAD, G4-5H, and G4(MP2)-6X emerge as excellent performers, with mean absolute deviations (MADs) from the benchmark W2w values of 0.9-1.4 kJ mol -1 . However, for the NACl RSEs, G4 is the best performer, with an MAD of 1.7 kJ mol -1 . The BDEs of both NAH and NACl bonds represent a challenge for DFT procedures. In particular, only a handful of functionals (namely, B3P86, M05-2X, M06-2X, and ROB2-PLYP) perform well, with MADs 4.5 kJ mol À1 for both bond types. Nearly all of the considered DFT procedures perform signifi-

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“…It has been shown that N-chlorinated species are more susceptible to photodegradation, mostly due to the homolytic bond dissociation energy (BDE), which is lower for the N-Cl bond than for the corresponding N-H bond. 18 The ease of formation of N-centered radicals has been reported for a series of chloramines, which play an important role in environmental chemistry and biochemistry. [19][20][21][22][23] Once formed, the N-centered radical 1a can undergo fast protonation yielding the radical cation 1b.…”

Section: Resultsmentioning

confidence: 99%

The chemical fate of paroxetine metabolites. Dehydration of radicals derived from 4-(4-fluorophenyl)-3-(hydroxymethyl)piperidine

et al. 2013

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Quantum chemical calculations have been used to model reactions which are important for understanding the chemical fate of paroxetine-derived radicals in the environment. In order to explain the experimental observation that the loss of water occurs along the ( photo)degradation pathway, four different mechanisms of radical-induced dehydrations have been considered. The elimination of water from the Ncentered radical cation, which results in the formation of an imine intermediate, has been calculated as the most feasible process. The predicted energy barrier (ΔG # 298 = 98.5 kJ mol −1 ) is within the barrier limits set by experimental measurements. All reaction intermediates and transition state structures have been calculated using the G3(MP2)-RAD composite procedure, and solvent effects have been determined using a mixed (cluster/continuum) solvation model. Several new products, which comply with the available experimental data, have been proposed. These structures could be relevant for the chemical fate of antidepressant paroxetine, but also for biologically and environmentally related substrates.

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Effect of Substituents on the Strength of N–X (X = H, F, and Cl) Bond Dissociation Energies: A High-Level Quantum Chemical Study

Cited by 33 publications

References 70 publications

A dataset of highly accurate homolytic NBr bond dissociation energies obtained by Means of W2 theory

A dataset of highly accurate homolytic NBr bond dissociation energies obtained by Means of W2 theory

NH and NCl homolytic bond dissociation energies and radical stabilization energies: An assessment of theoretical procedures through comparison with benchmark‐quality W2w data

The chemical fate of paroxetine metabolites. Dehydration of radicals derived from 4-(4-fluorophenyl)-3-(hydroxymethyl)piperidine

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