Abstract
Quantum chemical calculations of the IR spectra, dipole moments, and enthalpies for the optimized geometries of dominant Equatorial (EQ) and Axial (AX) conformers of R-(+)-3-methylcyclohexanone (R3MCH) were performed in 11 common solvents of different polarity and nature, in the framework of polarizable continuum model (PCM). Density Functional Theory (DFT) involving exchange–correlation functional B3LYP and aug-cc-pVTZ basis set were used. The IR calculations of the individual conformers of R3MCH in CCl4 yielded two distinct vibrational modes at 1086.13 cm−1 and 1030.86 cm−1 that were identified as unique markers of the EQ and AX conformers, respectively. By monitoring the calculated peaks of these two markers in 11 different solvents, a linear correlation between the EQ and AX markers’ intensities and frequencies with solvent polarity was observed. This correlation was directly related to the dipole moment orientation of each conformer. Upon increasing solvent polarity, the mode frequency of the EQ and AX markers experienced hypsochromic (blue) and bathochromic (red) shifts, respectively. A weak linear correlation was observed between the EQ and AX enthalpy difference as a function of solvent polarity.
Published Version
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