115252-80-7Relevant academic research and scientific papers
Polarization Spectroscopy and ab Initio Study of Photooriented Matrix-Isolated Isotopomers of Phthalic Anhydride. Assignment of the Infrared Absorption Spectrum
Biernacki, Peter R.,Kaszynski, Piotr,Hess, B. Andes,Thulstrup, Erik W.,Radziszewski, Juliusz G.
, p. 6309 - 6316 (1995)
In this paper we provide an assignment of symmetries for all transitions observed in the infrared spectrum of phthalic anhydride (1a), based on data determined from polarization studies of photooriented 1a.Photoselection, using two electronic transitions in phthalic anhydride 1a, at 34083 and 40650 cm-1 and of A1 and B2 symmetry, respectively, produced two differently oriented uniaxial samples of the anhydride immobilized in neon and other noble-gas matrices.Subsequent polarization measurements in the infrared region, combined with polarized Raman data, allowed a complete determination of transition moment directions for all observed fundametal vibrations.To facilitate definitive spectral assignments, we studied three isotopomers of 1a: 1,2-(13)C labeled phthalic anhydride (1b), the perdeuterated phthalic anhydride (1c), and the α-13C-labeled compound (1d).Absolute infrared absorption intensities were determined for all observed transitions utilizing absolute infrared absorption intensities of CO and CO2, formed in equimolar amounts with o-benzyne (2) in phototransformations of 1.Interpretation of the experimental results and the final assignments were aided by quantum mechanical modeling at the SCF/6-31G** level.
Mass spectrometry of benzyne and cyclopentadienylideneketene
Monsandl, Thomas,MacFarlane, Graham,Flammang, Robert,Wentrup, Curt
, p. 1076 - 1083 (2010)
The formation of cyclopentadienylideneketene 2 and benzyne 1 in flash vacuum thermolysis reactions is investigated by on-line mass spectrometry. Compounds 13, 14, and 15 all afford ketene 2, which decomposes to benzyne and CO in the high-temperature regime. Cyclopentadienylideneketene 2 is stable on the microsecond time-scale of neutralization-reionization experiments. Collisional activation mass spectrometry of m/z 76 from 14, 15, and 5 indicates that the C6H4·+ ions most likely undergo ring opening in the mass spectrometer.
Pitfalls in the photoelectron spectroscopic investigations of benzyne. photoelectron spectrum of cyclopentadienylideneketene
Chrostowska, Anna,Pfister-Guillouzo, Genevieve,Gracian, Franoise,Wentrup, Curt
experimental part, p. 1084 - 1090 (2011/04/15)
The 9.24 eV ionization energy often quoted in photoelectron spectroscopic investigations of benzyne is not due to benzyne 1 but to benzene, C 6H6. The 8.9 eV ionization is not due to benzyne either but to cyclopentadienylideneketene 12 when a 10.2 eV band is also present, or to biphenylene 5 when a 7.6 eV band is simultaneously present. Cyclopentadienylideneketene 12 has been generated by flash vacuum thermolysis of four different precursors, which permit a linking of infrared, mass, and photoelectron spectroscopic observations.
Infrared spectrum of o-benzyne: Experiment and theory
Radziszewski, Juliusz G.,Hess Jr., B. Andes,Zahradnik, Rudolf
, p. 52 - 57 (2007/10/02)
The complete set of vibrational frequencies and absolute infrared intensities has been determined for o-benzyne and two of its isotopomers: C6D4 and 1,2-13C2C4H4. In addition, for the majority of the transitions symmetries were assigned from infrared linear dichroism of the matrix-isolated samples, photooriented with polarized light during several photochemical transformations. Thermal relaxation of the high static pressure created by the initial photofragmentation causes dramatic changes of the fine site structure of each band of o-benzyne and results in a single-site infrared absorption spectra. A high-resolution, single-site vibrational spectrum was also obtained independently from laser hole-burning experiments. Band-shape analysis in different inert gas matrices (Ne, Ar, Xe, N2, and CO) greatly facilitates the correlation of isotopomer bands with those of unlabeled o-benzyne. The triple bond stretching vibration appears at 1846 cm-1 in a Ne matrix, with an experimental absolute intensity of 2.0 ± 0.4 km/mol in the unlabeled o-benzyne and is polarized along the symmetry axis. It is red-shifted by 2 cm-1 in the perdeutero-o-benzyne and by 53 cm-1 in the doubly 13C-labeled compound, in very good agreement with our theoretical prediction (MP2/6-31G**) and previous gas-phase data for o-benzyne.
