The NH2-inversion potential function in the Ã1b2 electronic state of aniline: Evidence for planarity

Hollas, J. Michael; Howson, Mark R.; Ridley, Trevor; Halonen, Lauri

doi:10.1016/0009-2614(83)80253-x

Cited by 90 publications

(25 citation statements)

References 8 publications

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“…3,4 Upon electronic excitation to the S 1 state, the amino hydrogens move significantly closer to the phenyl ring plane 5,6 and the amino inversion occurs on an essentially barrierless quartic potential. 7 Together these observations indicate the significantly enhanced conjugation that is present in the excited electronic state.…”

Section: Introductionmentioning

confidence: 88%

Electronic spectroscopy and molecular structure of jet-cooled diphenylamine and diphenylamine derivatives

Tretiakov

Cable

1997

The Journal of Chemical Physics

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Articles you may be interested inLaser induced fluorescence and resonant two-photon ionization spectroscopy of jet-cooled 1-hydroxy-9,10anthraquinone J. Chem. Phys. 122, 034304 (2005); 10.1063/1.1829977 H atom transfer along an ammonia chain: Tunneling and mode selectivity in 7-hydroxyquinoline ( NH 3 ) 3Resonance enhanced multiphoton ionization spectroscopy of jet cooled 12 C 32 S 2 and 12 C 34 S 32 S from 45 500 to 48000 cm−1 Vibrationally resolved electronic spectra of diphenylamine, three deuterated isotopomers, and both para-methyl and para-fluoro substituted derivatives have been recorded in a supersonic jet expansion using resonantly enhanced two-photon ionization. Analysis of these spectra, supported by ab initio calculations, has been used to determine the gas phase structure of diphenylamine. In both the ground and first excited singlet states, an effective C 2 symmetry structure is found in which the nitrogen atom is in a planar configuration and the phenyl rings adopt equal torsional angles. Calculations suggest that large-amplitude motion along the nitrogen inversion coordinate is possible in the ground electronic state. Isotopic substitutions have been used to assign the two low-frequency Franck-Condon active modes to different admixtures of symmetric phenyl torsion and bending about the central nitrogen. Electronic excitation to the S 1 state results in a decrease in the phenyl torsional angles of 7.4°and an increase in the C-N-C bond angle of 4.0°. While spectra of both the para mono-and dimethyl derivatives as well as the para-diflouro derivative indicate that little change occurs in either the physical or electronic structure of the basic chromophore, the spectrum of the monosubstituted para-fluoro derivative is indicative of a substantial perturbation to both.

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Section: Introductionmentioning

confidence: 88%

Electronic spectroscopy and molecular structure of jet-cooled diphenylamine and diphenylamine derivatives

Tretiakov

Cable

1997

The Journal of Chemical Physics

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“…However, some of these latter assignments have been disputed; in particular, I 0 1 and I 0 3 are symmetry forbidden in C 2v . [37][38][39] The current view is that S 1 aniline is a planar molecule with a near-zero inversion barrier. Its S 1 inertial defect is ⌬IϭϪ0.241 amu Å 2 , 34 significantly less than the ground state.…”

Section: ͑2͒mentioning

confidence: 99%

High resolution electronic spectroscopy of 1-aminonaphthalene: S0 and S1 geometries and S1←S0 transition moment orientations

Berden

Meerts

Plusquellic

et al. 1996

The Journal of Chemical Physics

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Fluorescence excitation spectroscopy at both vibrational and rotational resolution has been used to probe the changes in energy, electronic distribution, and geometry that occur when 1-aminonaphthalene ͑1AN͒ absorbs light at ϳ332 nm. The 0 0 0 band of the S 1 ←S 0 transition of 1AN is red shifted by nearly 2000 cm Ϫ1 with respect to the corresponding band of naphthalene. Additionally, it is mainly b-axis polarized, unlike the corresponding bands of naphthalene and other 1-substituted naphthalenes. Thus, 1 L a / 1 L b state reversal occurs on 1-substitution of naphthalene with an NH 2 group. The S 0 state of 1AN is pyramidally distorted at the nitrogen atom. Additionally, the NH 2 group is rotated by ϳ20°about the C-NH 2 bond. Excitation of 1AN to the zero-point vibrational level of its S 1 state reduces the C-NH 2 bond length by ϳ0.2 Å and flattens the NH 2 group along both out-of-plane coordinates. Other vibronic bands in the S 1 ←S 0 transition exhibit significantly different rotational constants, inertial defects, and transition moment orientations. An explanation for these findings is given that is based on the well-known conjugative properties of the NH 2 group in chemically related systems.

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“…Although virtually nothing is known about this mode in PABz, the situation appears to be rather similar to that in aniline, which has been studied in great detail in both the neutral and cationic state. 25,[34][35][36][37][38][39] Neutral ground state aniline is bent and the NH 2 inversion mode shows a symmetric double-well potential. In the S 1 electronically excited state, the molecule is planar and the mode is known to be a large amplitude strongly anharmonic vibration.…”

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confidence: 99%

Infrared multiple photon dynamics and spectroscopy of cationic PABA and its dehydroxylated fragment ion

Moore

Meijer

Helden

2004

Phys. Chem. Chem. Phys.

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The gas-phase infrared spectra of cationic para-amino benzoic acid (PABA, H 2 N-C 6 H 4 -COOH) and its dehydroxylated fragment ion, the para-amino benzoyl (PABz, H 2 N-C 6 H 4 -CO) cation, are presented in the 500-2500 cm À1 range. The spectra are obtained via mass-selective infrared multiple photon dissociation (IRMPD) using a continuously tunable free electron laser. Although both spectra are in good overall agreement with results from density functional theory, some interesting discrepancies are also observed. Particularly in the spectrum of the PABz cation, the strongly anharmonic NH 2 out-of-plane bending mode causes substantial deviations from theory. The relative intensity of this out-of-plane bending mode in both the PABA and PABz cation spectra is much lower than calculated, similar to what has been reported for cationic aniline. For the PABz cation, two distinct fragmentation products are observed and recording the infrared spectra on these individual decay channels yields information on the dissociation mechanism. Moreover, it is experimentally shown that the decay rate into the two competing channels can qualitatively be described using statistical models.

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The NH2-inversion potential function in the Ã1b2 electronic state of aniline: Evidence for planarity

Cited by 90 publications

References 8 publications

Electronic spectroscopy and molecular structure of jet-cooled diphenylamine and diphenylamine derivatives

Electronic spectroscopy and molecular structure of jet-cooled diphenylamine and diphenylamine derivatives

High resolution electronic spectroscopy of 1-aminonaphthalene: S0 and S1 geometries and S1←S0 transition moment orientations

Infrared multiple photon dynamics and spectroscopy of cationic PABA and its dehydroxylated fragment ion

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