Effect of Intra- and Intermolecular Interactions on the Properties of para-Substituted Nitrobenzene Derivatives

Szatyłowicz, Halina; Stasyuk, Olga A.; Guerra, Célia Fonseca; Krygowski, Tadeusz M.

doi:10.3390/cryst6030029

Cited by 21 publications

(21 citation statements)

References 46 publications

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“…Attachment of the electron-donating amino group, or its anion NH − , to a nitrobenzene system leads to an increase of electron-accepting power of the nitro group. It is well evidenced by more negative values of cSAR(NO 2 ) in para-nitroaniline (pNA) and para-nitroanilide anion (pNA anion) than in nitrobenzene, as shown in Table 3 [25]. A comparison of the absolute cSAR(NO 2 ) values in pNA and nitrobenzene (coplanar conformation of NO 2 ) gives a difference of 0.073 e, i.e., the addition of an amino group increases the electron-acceptor character of NO 2 by 50%.…”

Section: Classical Substituent Effectmentioning

confidence: 81%

“…Physicochemical properties of the nitro group, both from the viewpoints of structural and quantum chemical research, have been presented in many papers [2,3,[22][23][24]. The structure of the nitro group undergoes deformations due to intramolecular or intermolecular interactions, as documented by numerous experimental data [25]. These deformations can undoubtedly cause changes in the sigma and pi electron structure of the whole molecule; details are presented later in this work.…”

Section: Introductionmentioning

confidence: 99%

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Substituent effects of nitro group in cyclic compounds

2020

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Numerous studies on nitro group properties are associated with its high electron-withdrawing ability, by means of both resonance and inductive effect. The substituent effect of the nitro group may be well described using either traditional substituent constants or characteristics based on quantum chemistry, i.e., cSAR, SESE, and pEDA/sEDA models. Interestingly, the cSAR descriptor allows to describe the electron-attracting properties of the nitro group regardless of the position and the type of system. Analysis of classical and reverse substituent effects of the nitro group in various systems indicates strong pi-electron interactions with electron-donating substituents due to the resonance effect. This significantly affects the pi-electron delocalization of the aromatic ring decreasing the aromatic character, evidenced clearly by HOMA values. Use of the pEDA/sEDA model allows to measure the population of electrons transferred from the ring to the nitro group. Keywords Nitro group. Substituent effects. Molecular modeling. Sigma and pi electron structure. Substituent effect stabilization energy. Charge of the substituent active region This review is dedicated to our friend and mentor Professor Tadeusz Marek Krygowski of the Department of Chemistry of the Warsaw University in gratitude for his guidance, support, and engagement in our research.

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Section: Classical Substituent Effectmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Substituent effects of nitro group in cyclic compounds

2020

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“…12. The role of the intramolecular charge transfer is nicely documented when we look at the HOMA change due to the rotation of the nitro group in para-nitroanilines [148].…”

Section: Disubstituted π-Electron Systemsmentioning

confidence: 86%

On the relations between aromaticity and substituent effect

2019

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Aromaticity/aromatic and substituent/substituent effects belong to the most commonly used terms in organic chemistry and related fields. The quantitative description of aromaticity is based on energetic, geometric (e.g., HOMA), magnetic (e.g., NICS) and reactivity criteria, as well as the properties of the electronic structure (e.g., FLU). The substituent effect can be described using either traditional Hammett-type substituent constants or characteristics based on quantum-chemistry. For this purpose, the energies of properly designed homodesmotic reactions and electron density distribution are used. In the first case, a descriptor named SESE (energy stabilizing the substituent effect) is obtained, while in the second case cSAR (charge of the substituent active region), which is the sum of the charge of the ipso carbon atom and the charge of the substituent. The use of the above-mentioned characteristics of aromaticity and the substituent effect allows revealing the relationship between them for mono-, di-, and polysubstituted π-electron systems, including substituted heterocyclic rings as well as quasi-aromatic ones. It has been shown that the less aromatic the system, the stronger the substituent influence on its π-electron structure. In all cases, when the substituent changes number of π-electrons in the ring in the direction of 4N+2, its aromaticity increases. Intramolecular charge transfer (a resonance effect) is privileged in cases where the number of bonds between the electron-attracting and electron-donating atoms is even. Quasi-aromatic rings, when attached to a truly aromatic hydrocarbon, simulate well the Boriginal^aromatic rings, alike the benzene. For larger systems, a long-distance substituent effect has been found.

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“…So it is not surprising a great number of crystal structures deposited in the Cambridge Structural Database [11] (CSD) amounting over 38,000 records, as it has been noted recently [12].…”

Section: Introductionmentioning

confidence: 99%

Classical and reverse substituent effects in meta- and para-substituted nitrobenzene derivatives

et al. 2017

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Electron-accepting properties of the nitro group were studied in a series of meta-and para-X-substituted nitrobenzene derivatives (X = NMe 2 , NH 2 , OH, OMe, CH 3 , H, F, Cl, CF 3 , CN, CHO, COMe, CONH 2 , COOH, COCl, NO 2 , NO). For this purpose Hammett-like approaches were applied based on quantum chemistry modeling; the B3LYP/6-311++ G(d,p) method was used. The substituent effect (SE) was characterized by the mutually interrelated descriptors: the charge of the substituent active region, cSAR(X), and substituent effect stabilization energy, SESE, as well as substituent constants, σ. Classical SE is realized by dependences of the structural parameters of the nitro group (ONO angle and NO bond lengths) and cSAR(NO 2 ) on the above mentioned SE descriptors. The reverse substituent effect was clearly documented by a comparison of cSAR(X) values for monosubstituted benzenes, meta-and para-substituted nitrobenzenes as well as, additionally, for meta-and para-X-substituted anilines. For para-substituted systems the electron-accepting ability of the nitro group increases from cSAR(NO 2 ) = −0.170 up to −0.284 in dinitrobenzene and nitroaniline, respectively.

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Effect of Intra- and Intermolecular Interactions on the Properties of para-Substituted Nitrobenzene Derivatives

Cited by 21 publications

References 46 publications

Substituent effects of nitro group in cyclic compounds

Substituent effects of nitro group in cyclic compounds

On the relations between aromaticity and substituent effect

Classical and reverse substituent effects in meta- and para-substituted nitrobenzene derivatives

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