Experimental and ab-initio calculated vcd spectra of the first OH-stretching overtone of (1R)-(-) and (1S)-(+)-endo-borneol

The near infrared (NIR) absorption and NIR-vibrational circular dichroism (NIR-VCD) spectra
of dilute solutions of the two enantiomers of endo-borneol have been measured in the first
OH-stretching overtone region (1600–1300 nm). By density functional theory (DFT) we calculate
mechanical parameters, i.e. the harmonic mechanical frequency and the anharmonicity constant
for the OH stretching, and anharmonic electrical parameters; i.e. the dependence on OH-bond
length of atomic polar tensors and atomic axial tensors. We evaluate transition integrals for the
calculations of rotational and dipole strengths by Morse anharmonic wavefunctions depending on
mechanical harmonic frequencies and mechanical anharmonicity parameters that are calculated
ab initio. Experimental and calculated spectra compare quite well and this fact allows us to
associate differently signed NIR-VCD features with different conformational states of the
OH-bond. Absorption features for the fundamental and for the second overtone of the OH
stretching are also compared with experiment.