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Further calculations on the internal rotation spectrum of phenol
Author(s) -
Smeyers Y. G.,
HernándezLaguna A.
Publication year - 1982
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560220403
Subject(s) - cndo/2 , rotation (mathematics) , symmetry (geometry) , tilt (camera) , internal rotation , chemistry , rotor (electric) , physics , molecular physics , atomic physics , geometry , quantum mechanics , molecule , mathematics , mechanical engineering , engineering
The influence of a small deformation of CĈO angle in phenol (tilt), into the rotational far‐infrared ( FIR ) spectrum is analyzed using several approaches. In all of them, the CNDO /2 method is used to determine the potential energy functions. In a first step, the CO bond and the rotation axis are both supposed to coincide with the C 2 symmetry axis of the phenyl group. With this assumption the torsional frequencies are calculated in both the symmetric and asymmetric rotor approximations. In a second step, the tilt of the COH bond is determined theoretically and found to be −3°, measured from the C 2 symmetry axis, the COH bond crossing this axis, Using this second geometry, and taking as the rotation axis the C 2 axis, the torsional frequencies are again determined in both approximations. An improvement of the calculated transition energies is encountered at each stage of the calculation, when compared with experimental data. Finally the importance of the introduction of a tilt into the FIR torsional frequency calculations is discussed.