Showing papers by "Thomas Bally published in 1996"
TL;DR: In this paper, the geometries and force fields of phenylcarbene and cycloheptatrienylidene (CHT) in their singlet and triplet electronic states as well as of CHTE and bicyclo[4.1.0]heptatriene and the transition states for the formation and decay of the latter were evaluated by various methods.
Abstract: The geometries and force fields of phenylcarbene (PC) and cycloheptatrienylidene (CHT) in their singlet and triplet electronic states as well as of cycloheptatetraene (CHTE) and bicyclo[4.1.0]heptatriene (BCT) and the transition states for the formation and decay of the latter were evaluated by various methods. Relative single point energies were calculated at the CCSD(T)/cc-pVDZ//BLYP/6-31G* level. Finally, the effects of extending the basis set to triple-ζ quality were estimated by (R)MP2 calculations and carried over proportionally to CCSD(T). These calculations show that CHTE which has a strongly distorted allenic structure is the most stable species on that part of the C(CH)6 surface which was examined in the present study, followed by planar 3PC. The strained BCT is found to be nearly degenerate in energy with 1PC, but the high activation energy for its formation from 1PC together with the low activation energy for ring-opening to CHTE suggests that this species cannot persist under the experimental...
139 citations
TL;DR: In this article, the resonance Raman spectrum of the 1,3-butadiene radical cation generated by γ-irradiation in a Freon glass was analyzed with the help of density functional theory calculations and a recently published scaled quantum mechanical force field.
Abstract: We report the resonance Raman spectrum of the 1,3-butadiene radical cation generated by γ-irradiation in a Freon glass. The spectrum is excited at 550 nm in resonance with the first absorption band. The spectrum, which is interpreted with the help of density functional theory calculations and a recently published scaled quantum mechanical force field, indicates the presence of both the s-trans and the s-cis rotamers of the butadiene radical cation.
17 citations
TL;DR: In this article, the resonance Raman spectra of the radical cations of three deuterated derivatives of 1,3-butadiene were used to generate a scaled quantum mechanical force field of butadiene radical cation based on B3LYP/6-31G second derivatives.
Abstract: The resonance Raman spectra of the radical cations of three deuterated derivatives of 1,3-butadiene are reported. Together with the data for the parent compound (cf.: Keszthelyi, T.; Wilbrandt, R.; Bally, T. J. Phys. Chem. 1996, 100, 16843), 22 frequencies of totally symmetric fundamentals are available to complement 29 previously obtained IR data for the same compounds (Tang, W; Zhang, X.-L., Bally, T. J. Phys. Chem. 1993, 97, 4373) and to generate a new and improved scaled quantum mechanical force field of butadiene radical cation based on B3LYP/6-31G* second derivatives. After fitting those with 13 scaling factors, the resulting force field reproduces all 51 observed fundamental vibrations of the four isotopomers with a root-mean-square deviation of 6.03 cm-1 (10.6 cm-1 for the 11 strongly anharmonic C−H/C−D stretches, 3.92 cm-1 for the remaining 40 modes). It allows the first experimentally based prediction of the stretching force constant for the central C−C bond and corrects the previous ones for t...
16 citations