0000000000347196
AUTHOR
Walter Thiel
Konformation sterisch gehinderter Anilin-Kationradikale und Benzyl-Kationen/On the Conformation of Sterically Hindered Aniline Cation Radicals and Benzyl Cations
Abstract A series of aniline cation radicals have been generated in a flow apparatus, and their ESR spectra have been recorded and interpreted. The data show that the NR1R2 substituents are less twisted in these systems than the CR1R2 substituents in the isoelectronic but sterically less hindered benzyl radicals, in accordance with MNDO calculations. The conformations of these systems are strongly influenced by electronic π-resonance effects which limit the usefulness of steric models for structural predictions. The results suggest that the CR1R2 substituent in the benzyl cations is less twisted than in the corresponding radicals. An ESR measurement of these radicals should therefore provid…
Anharmonic force fields from analytic CCSD(T) second derivatives: HOF and F2O
The recent implementation of analytic second derivatives for CCSD(T) (coupled cluster theory with single and double excitations augmented by a perturbational treatment of connected triple excitations) has been combined with a numerical finite difference procedure to calculate cubic and semidiagonal quartic force fields. Computational details of this approach are outlined. Applications are reported for HOF and F2O. The CCSD(T) results are in excellent agreement with experiment and represent a substantial improvement over the results obtained from MP2 (Mo/ller–Plesset second-order perturbation theory).
Ab InitioCalculations and High-Resolution Spectroscopy of the Bending Pentad of SiH2D2in the 10–16 μm Region
Abstract The SiH 2 D 2 asymmetric top has nine vibrational modes, five of them forming a pentad strongly perturbed by Coriolis interactions. High-level ab initio calculations of SiH 2 D 2 have been performed which yield numerous spectroscopic parameters related to the harmonic and anharmonic force fields. The bending pentad comprising ν 4 (A 1 ), ν 7 (B 1 ), ν 5 (A 2 ), ν 9 (B 2 ), and ν 3 (A 1 ) has been studied by high-resolution Fourier transform spectroscopy; the region 600–1050 cm −1 has been investigated with a resolution of ca. 4 × 10 −3 cm −1 . Raman BOXCARS spectroscopy has been used for the infrared inactive ν 5 band. The Raman apparatus function was 0.0054 cm −1 . Assignments of …