Vibrational optical activity study of trans-succinic-d(2) anhydride

The (R-,R-) and (S-,S-) enantiomers of the trans-dideuteriosuccinic anhydride were synthesized, and their infrared absorption, vibrational circular dichroism (VCD), and Raman spectra were measured. Ab initio quantum mechanical harmonic force fields (FFs) were calculated at the SCF (6-31G**), MP2, and density functional (DFT) levels, transition frequencies were generated, and the fundamental vibrational transitions were assigned. Anharmonic corrections to the SCF and DFT FFs were generated using numerical differentiation to obtain cubic and selected quartic terms. Good overall agreement was observed for the vibrational frequencies and the IR absorption intensities between experimental and calculated results. Computations of the Raman and VCD intensities were carried out at the SCF level, the latter using the magnetic field perturbation method of Stephens and co-workers. The computed Raman intensities are in qualitative agreement with the main experimental features. For the mid-IR VCD transitions, full sign agreement was obtained between the experiment and computations for the (S,S) isomer, enabling the absolute configuration of the title compound to be determined unambiguously.