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Structural and vibrational analysis of the OH torsional motion in difluorohydroxyborane
Author(s) -
Melendez F. J.,
MuñozCaro C.,
Niño A.,
SandovalLira J.,
RangelHuerta A.
Publication year - 2011
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.22987
Subject(s) - chemistry , anharmonicity , dipole , hamiltonian (control theory) , moment of inertia , intramolecular force , fluorine , atomic physics , molecular physics , molecule , computational chemistry , physics , classical mechanics , stereochemistry , quantum mechanics , mathematical optimization , mathematics , organic chemistry
Abstract In this work, we present a complete structural and vibrational analysis of the OH torsional motion in difluorohydroxyborane (BF 2 OH) at the HF/aug‐cc‐pVTZ, MP2(full)/aug‐cc‐pVTZ, and CCSD/aug‐cc‐pVTZ theory levels. After full relaxation of the geometry, the equilibrium structure is found in a planar conformation of C s symmetry. The difference in the two BF distances suggests the existence of a nonbonded interaction between the fluorine and oxygen atoms. The structural and energetic variation of BF 2 OH as a function of the OH torsional angle is considered. The torsional barrier, at the CCSD/aug‐cc‐pVTZ level, and including the effect of the zero‐point energy of the remaining vibrations, is found 2,728 cm −1 . In addition, an anharmonic Hamiltonian for the OH torsional mode is presented and variationally solved. To simplify the treatment and to classify the energy levels, BF 2 OH is classified under a G 4 nonrigid group accounting for the inversion symmetry of the molecule and the interchange of the fluorine atoms. The computed torsional energy levels exhibit a very small inversion splitting. The torsional spectrum is simulated considering the dipole moment components along the principal axes of inertia as an explicit function of the torsional coordinate. We observe three dominant bands in the spectrum formed by doublets corresponding to ν 9 = 0 → 1, 2 transitions. The fundamental is an a ‐type, Franck–Condon, transition. This is the strongest and appears at 466.80 cm −1 with relative intensity 0.4312. The ν 9 = 0 → 2 bands correspond to doublets of b ‐ and c ‐type, i.e., Herzberg–Teller transitions. These are two overlapping bands found at 890.92 and 890.94 cm −1 with intensity 0.2207 for the b ‐type band and 0.2193 for the c ‐type band. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011