Similarity in Dissymmetry Factor Spectra: A Quantitative
Measure of Comparison between Experimental and Predicted Vibrational
Circular Dichroism
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Abstract
To quantitatively determine the agreement
between experimental
and calculated vibrational circular dichroism (VCD) spectra, a new
approach, based on the similarity of dissymmetry factor spectra has
been developed and implemented. This method, which places emphasis
on robust regions both in the experimental and in the calculated spectra,
has been tested with six chiral compounds of known absolute configurations,
namely, (<i>R</i>)-(+)-3-chloro-1-butyne, (3<i>R</i>)-(+)-methylcyclopentanone, (3<i>R</i>)-(+)-methylcyclohexanone,
(1<i>S</i>)-(−)-α-pinene, (1<i>R</i>)-(+)-camphor, and (<i>S</i>)-(+)-epichlorohydrin. The
criterion of maximum overlap among experimental and calculated dissymmetry
factor spectra is shown to have definite advantages over those using
maximum overlap among VCD or absorption spectra individually. The
new method provides a better assessment of the comparison between
experimental observations and quantum chemical VCD predictions and
improves the confidence in the assignment of absolute configurations