| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2000: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1999: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
Recently, we showed using ab initio MO calculations at levels of CASSCF and MRSDCI that the global minimum of the benzene dimer cation, (C_6H_6)_2^+, are at distorted sandwich C_<2h> geometries, which is lower than sandwich D_<6h> and T-shaped C_<2v> structures by 0.016 and 0.162 eV, respectively. In this study, we performed similar calculations for the benzene trimer cation, (C_6H_6)_3^+, and found that that the global minimum of the trimer cation is the distorted C_<2v> sandwich structure, which is 0.032 eV lower than the D_<6h> sandwich structure. The dissociation energy (D_e). relative to (C_6H_6)_2^++C_6H_6 was calculated to be 0.43 eV, in comparison to the experimental value (D_0) of 0.34±0.02 eV.Our calculations revealed that most of the charge of the trimer cation is localized in the central benzene ring, whose gross charge is +0.9. This observation contrasts with speculations by experimentalists that the charge is localized in the dimer core or delocalized over all three benze
… More
ne rings.
We investigated also possible geometrical structures for the phenol dimer and its cation. The calculated binding energy of the phenol dimer reasonably agrees with experimental and other theoretical values. The calculated binding energies of the dimer cation are about 28 kcal/mol at the MP2 and CASSCF levels ; this is more than three times larger than in the neutral dimer. The OH stretching frequencies (3616〜3618 cm^<-1>) of the PAP in the phenol dimer cation are in good agreement with the observed value (3620±3 cm^<-1>). Those of the PDP in the dimer cation are calculated to be 2434〜2447 cm^<-1>, which are 1210〜1223 cm^<-1> smaller than that of bare phenol. The large reduction of the OH stretching frequency of the PDP in the phenol dimer cation can be attributed to elongation of the 0-H bond involved in the hydrogen bond on the formation of a stronger hydrogen bond in the cation than in the neutral dimer. These values for the OH stretching frequencies of the PDP in the phenol dimer cation will serve for future reference. Less
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