MEASUREMENT AND CALCULATION OF ABSOLUTE ROTATIONAL STRENGTHS FOR CAMPHOR, ALPHA-PINENE, AND BORNEOL

Experimental dipole and rotational strengths of the three optically ac tive terpenes were compared to those obtained from the magnetic field perturbation (MFP) and vibronic coupling theory (VCT), and the results were analyzed in order to facilitate future extension of current vibr ational circular dichroism (VCD) simulation techniques to bigger molec ules. Experimental VCD patterns could be faithfully reproduced by both calculations, but the absolute VCD intensities are usually underestim ated. The size of the basis set is the main limitation in both the MFP and VCT calculations. Harmonic frequencies and dipolar strengths obta ined by Hartree-Fock and five density functional methods are compared to experiment for cr-pinene. For borneol, a natural occurrence and spe ctral representation of its conformers are discussed on the basis of c omparison of the theoretical and experimental frequencies and VCD and absorption intensities.