Structure, dipole moment and large amplitude motions of 1-benzofuran

Maris, Assimo; Giuliano, B. M.; Melandri, Sonia; Ottaviani, Paolo; Camináti, Walther; Favero, Laura B.; Velino, Biagio

doi:10.1039/b507795h

Cited by 15 publications

(11 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The geometric parameters and the vibrational frequencies of BF, BT, IN, DBF, DBT, and CA were calculated at the MPWB95/6-31+G(d,p) level and compared with the experimental values in Tables S3–S5 of Supporting Information. The results at the MPWB95/6-31+G(d,p) level were in accordance with the experimental data, and the average relative error remained within 3.3% for the geometrical parameters [46,47,48,49,50], and less than 5.7% for the vibrational frequencies of BF, BT, IN, DBF, DBT, and CA [51,52,53,54]. To verify the reliability of the energies, we calculated the reaction heats for benzofuran (C 8 H 6 O) + cyclopentadiene (C 5 H 6 ) → dibenzofuran (C 12 H 8 O) + CH 4 , benzothiophene (C 8 H 6 S) + cyclopentadiene (C 5 H 6 ) → dibenzothiophene (C 12 H 8 S) + CH 4 , and indole (C 8 H 7 N) + cyclopentadiene (C 5 H 6 ) → carbazole (C 12 H 9 N) + CH 4 at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level.…”

Section: Resultssupporting

confidence: 78%

The Gas-Phase Formation Mechanism of Dibenzofuran (DBF), Dibenzothiophene (DBT), and Carbazole (CA) from Benzofuran (BF), Benzothiophene (BT), and Indole (IN) with Cyclopentadienyl Radical

Gao

Zuo

et al. 2019

IJMS

View full text Add to dashboard Cite

Benzofuran (BF), benzothiophene (BT), indole (IN), dibenzofuran (DBF), dibenzothiophene (DBT), and carbazole (CA) are typical heterocyclic aromatic compounds (NSO-HETs), which can coexist with polycyclic aromatic hydrocarbons (PAHs) in combustion and pyrolysis conditions. In this work, quantum chemical calculations were carried out to investigate the formation of DBF, DBT, and CA from the reactions of BF, BT, and IN with a cyclopentadienyl radical (CPDyl) by using the hybrid density functional theory (DFT) at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. The rate constants of crucial elementary steps were deduced over 600−1200 K, using canonical variational transition state theory with a small-curvature tunneling contribution (CVT/SCT). This paper showed that the production of DBF, DBT, and CA from the reactions of BF, BT, and IN with CPDyl involved six elementary steps: the addition reaction, ring closure, the first H shift, C–C cleavage, the second H shift, and elimination of CH3 or H. The cleavage of the C–C bond was regarded as the rate-determining step for each pathway due to the extremely high barrier. The 1-methyl substituted products were more easily formed than the 4-methyl substituted products. The main products were DBF and 1-methyl-DBF, DBT and 1-methyl-DBT, and CA and 1-methyl-CA for reactions of BF, BT, and IN with CPDyl, respectively. The ranking of DBF, DBT, and CA formation potential was as follows: DBT and methyl-DBT formation > DBF and methyl-DBF formation > CA, and methyl-CA formation. Comparison with the reaction of naphthalene with CPDyl indicated that the reactions of CPDyl attacking a benzene ring and a furan/thiophene/pyrrole ring could be inferred to be comparable under high temperature conditions.

show abstract

Section: Resultssupporting

confidence: 78%

The Gas-Phase Formation Mechanism of Dibenzofuran (DBF), Dibenzothiophene (DBT), and Carbazole (CA) from Benzofuran (BF), Benzothiophene (BT), and Indole (IN) with Cyclopentadienyl Radical

Gao

Zuo

et al. 2019

IJMS

View full text Add to dashboard Cite

show abstract

“…Caminati et al have discussed the bond localisation of benzofuran,aheterocycle similart o1 H-indazole, based on the AGIBA effect, and assigned to the imbalance between its two principal canonicals tructures. [81,82] In both cases (Mills-Nixon and AGIBA), the bond alternation is explained by ad ominance of one of the resonant forms of benzene over the other because of the presence of the substituent(s). In aromatic molecules, consideration of the possible resonance formsi sk nown to be au seful, if not ap articularly precise tool.…”

Section: Compoundmentioning

confidence: 99%

Bond Length Alternation Observed Experimentally: The Case of 1H‐Indazole

Uriarte

Reviriego

Calabrese

et al. 2019

Chemistry A European J

View full text Add to dashboard Cite

Bond length alternation is a chemical phenomenon in benzene rings fused to other rings, which has been mainly predicted theoretically. Its physical origin is still not clear and has generated discussion. Here, by using a strategy that combines microwave spectroscopy, custom‐made synthesis and high‐level ab initio calculations, we demonstrate that this phenomenon is clearly observed in the prototype indazole molecule isolated in the gas phase. The 1H‐indazole conformer was detected by rotational spectroscopy, and its 17 isotopologues resulting from single and double heavy atom substitution (13C and 15N) were also unambiguously observed. Several experimental structures were determined and, in particular, the most useful semi‐experimental equilibrium structure (reSE), allowed determination of the heavy atom bond lengths to milli‐Ångstrom precision. The experimentally determined bond length alternation is estimated to correspond to 60:40 contributions from the two resonant forms of 1H‐indazole.

show abstract

“…This chemical phenomenon takes place in (multi)‐substituted benzenes and in benzene rings fused to small saturated rings. Despite its interest, there are not many cases where it has been possible to observe this effect experimentally [30–33] …”

Section: Resultsmentioning

confidence: 99%

Bond Length Alternation and Internal Dynamics in Model Aromatic Substituents of Lignin

et al. 2022

View full text Add to dashboard Cite

Broadband microwave spectra were recorded over the 2‐18 GHz frequency range for a series of four model aromatic components of lignin; namely, guaiacol (ortho‐methoxy phenol, G), syringol (2,6‐dimethoxy phenol, S), 4‐methyl guaiacol (MG), and 4‐vinyl guaiacol (VG), under jet‐cooled conditions in the gas phase. Using a combination of 13C isotopic data and electronic structure calculations, distortions of the phenyl ring by the substituents on the ring are identified. In all four molecules, the rC(1)‐C(6) bond between the two substituted C‐atoms lengthens, leading to clear bond alternation that reflects an increase in the phenyl ring resonance structure with double bonds at rC(1)‐C(2), rC(3)‐C(4) and rC(5)‐C(6). Syringol, with its symmetric methoxy substituents, possesses a microwave spectrum with tunneling doublets in the a‐type transitions associated with H‐atom tunneling. These splittings were fit to determine a barrier to hindered rotation of the OH group of 1975 cm−1, a value nearly 50 % greater than that in phenol, due to the presence of the intramolecular OH⋅⋅⋅OCH3 H‐bonds at the two equivalent planar geometries. In 4‐methyl guaiacol, methyl rotor splittings are observed and used to confirm and refine an earlier measurement of the three‐fold barrier V3=67 cm−1. Finally, 4‐vinyl guaiacol shows transitions due to two conformers differing in the relative orientations of the vinyl and OH groups.

show abstract

Structure, dipole moment and large amplitude motions of 1-benzofuran

Cited by 15 publications

References 32 publications

The Gas-Phase Formation Mechanism of Dibenzofuran (DBF), Dibenzothiophene (DBT), and Carbazole (CA) from Benzofuran (BF), Benzothiophene (BT), and Indole (IN) with Cyclopentadienyl Radical

The Gas-Phase Formation Mechanism of Dibenzofuran (DBF), Dibenzothiophene (DBT), and Carbazole (CA) from Benzofuran (BF), Benzothiophene (BT), and Indole (IN) with Cyclopentadienyl Radical

Bond Length Alternation Observed Experimentally: The Case of 1H‐Indazole

Bond Length Alternation and Internal Dynamics in Model Aromatic Substituents of Lignin

Contact Info

Product

Resources

About