A study on the structure and vibrations of diphenylamine by resonance-enhanced multiphoton ionization spectroscopy and <i>ab</i> <i>initio</i> calculations

Boogaarts, Maarten G. H.; Helden, Gert von; Meijer, Gerard

doi:10.1063/1.472640

Cited by 18 publications

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References 32 publications

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“…Based on calculated vibration frequencies, Choi and Kertesz [11] assigned the IR and Raman spectra of diphenylamine. The conclusion of that the N atom has a pyramidal coordination and the phenyl rings are nonequivalent agrees with the results of the experimental data of Boogaarts et al [12] who also performed ab initio calculations with the even larger 6-31G** basis set (including polarization p functions on H atoms). Similar results were also obtained for torsion angles (14.7o and 44.5o) and deviation of the H atom from the CNC plane (20.8o).…”

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“…Similar results were also obtained for torsion angles (14.7o and 44.5o) and deviation of the H atom from the CNC plane (20.8o). It is interesting to note that the geometry of the first electronically excited state (singlet), obtained in [12], correspond to a molecular conformation of C 2 symmetry with a planar coordination of bonds around the N atom. The nonequivalent orientation of the rings in the ground electronic state of diphenylamine is disputed by Tretiakov and Cable [13] who concluded that the vibrationally allowed electronic spectra of diphenylamine and three its deuterated analogs, obtained in expanded supersonic jet with resonance-enhanced two-photon ionization, better agree with a C 2 molecular geometry both in the ground and first excited singlet electronic state.…”

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Molecular Structure of Diphenylamine by Gas-Phase Electron Diffraction and Quantum Chemistry

et al. 2005

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Geometric parameters of the diphenylamine molecule were determined by gas-phase electron diffraction and quantum-chemical calculations. By gas-phase electron diffraction, the molecule has an asymmetric structure with torsion angles about N3C bonds of 345.6(23)o and 173.4(46)o, which agrees with RHF/6-31G** calculations. Density functional theory (DFT) calculations at the B3LYP/6-31G** level of theory lead to a C 2 molecular conformation in the ground electronic state. The principal experimental geometric parameters are as follows: bond lengths: C3N 1.417(1), C3C av 1.403(1) A; and bond angles: CNC 123.9(5)o, and NCC 121.5o (assumed) and 116.4o.Proceeding with a systematic research into the structure of phenylphosphines [133], here we present the results of a structural study of diphenyamine (HNPH 2 ). It is important to compare the conformations and structural parameters of mono-, di-and triphenylamines and -phosphines. The analysis of phenylphosphines is presented in [3]. The structure of gaseous diphenylamine has not been studied.Quantum-chemical calculations. Geometry optimization of the diphenylamine molecule was performed by both semiempirical [439] and ab initio methods [8, 10315]. In geometry optimization, the most important parameters that determine the conformation of this molecule are piramidality of the N atom (measured by the sum of its bond angles) and torsion angles of phenyl groups relative to the C3N3C plane (Fig. 1). In view of the possibility of free rotation of phenyl groups and also the low barrier to inversion of the N atom, a number of possible conformation have been suggested for diphenylamine in the literature. Geometry optimization by semiempirical methods in different approximations (CNDO/2, INDO, MINDO/3, and MNDO) leads to a molecular conformation in which the N atom possesses a pyramidal coordination and phenyl groups have different torsion angles relative to the CNC plane. Therewith, the C 3 C 2 NC 8 and C 9 C 8 NC 2 torsion angles and differences between them depend remarkably on the method used [5]. By contrast, the AM1-optimized conformation [8] is propeller-like and has C 2 symmetry with equal torsion angles (27.7o) and a planar coordination of bonds around the N atom. Moreover, Bredas et al. [8] have been the first who performed ab initio calculations of the diphenylamine molecule with the 3-21G basis set. The results of the latter calculation gave indirect evidence to show that the AM1 method is suitable for geometry optimization of diphenylamine and its analogs. Boyle [9] have optimized the geometry of diphenylamine molecule and some of its ortho-substituted analogs by the AM1 method and found that the global minimum corresponds to an asymmetric conformation with a pyramidal N atom and that the torsion angles of the phenyl rings relative to the CNC plane depend on the configuration of bonds around the N atom (planar or pyramidal). As follows from the results of ab initio calculations with the STO-3G and 6-31G basis sets [10], the most stable conformation possesses equal 10 11...

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Molecular Structure of Diphenylamine by Gas-Phase Electron Diffraction and Quantum Chemistry

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“…In the present experiment, the macropulse repetition rate is 5 Hz and the laser bandwidth is typically 0.5%-1.0% of the central frequency. The molecular beam spectrometer, including the two tunable pulsed UV laser systems, is operated at a 10 Hz repetition rate and has been described previously (Boogaarts, von Helden, & Meijer 1996). A scheme of the experimental setup is shown in Figure 1a.…”

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Infrared Spectroscopy of Jet-cooled Cationic Polyaromatic Hydrocarbons: Naphthalene[TSUP]+[/TSUP]

Piest¹,

Helden²,

Meijer³

1999

The Astrophysical Journal

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We present the infrared (IR) absorption spectrum of the jet-cooled naphthalene-Ar van der Waals cluster cation in the 400-1600 cm Ϫ1 range, which is expected to resemble closely the IR spectrum of the bare naphthalene cation. Cluster cations are produced in their ground states via resonance-enhanced two-color ionization. Subsequent irradiation of the ions with IR light of a free-electron laser causes cluster dissociation, if this light is resonant with IR-active transitions of the cationic cluster. Mass-selective measurement of the dissociated fraction as a function of IR wavelength yields the IR spectrum of the cationic cluster. Comparison with previously reported Ar matrix isolation spectra of naphthalene ϩ shows good agreement, with more bands observed in the present study. The IR spectrum observed is compared to a calculated spectrum of the naphthalene cation, allowing for unambiguous assignments of all the observed modes. The experimental method presented is generally applicable to obtain laboratory IR spectra of ionized polyaromatic hydrocarbons under astrophysically relevant conditions.

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“…10 While two extended low-frequency vibrational progressions in 62 and 90 cm Ϫ1 modes were observed, indicating that substantial structural changes occurred upon electronic excitation, no detailed structural or vibrational assignments were presented. Later, in conjunction with ab initio calculations and additional spectra of DPA van der Waals clusters, Boogaarts et al 11 presented evidence for a ground state structure of C 1 symmetry in which the central nitrogen atom was in a pyramidal bonding environment. The excited state, however, was calculated to have C 2 symmetry and a planar nitrogen.…”

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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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A study on the structure and vibrations of diphenylamine by resonance-enhanced multiphoton ionization spectroscopy and ab initio calculations

Cited by 18 publications

References 32 publications

Molecular Structure of Diphenylamine by Gas-Phase Electron Diffraction and Quantum Chemistry

Molecular Structure of Diphenylamine by Gas-Phase Electron Diffraction and Quantum Chemistry

Infrared Spectroscopy of Jet-cooled Cationic Polyaromatic Hydrocarbons: Naphthalene[TSUP]+[/TSUP]

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

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