VIBRATIONAL CIRCULAR DICHROISM OF TRANS-DICYANOCYCLOPROPANE AND

TRANS-TETRAHYDROFURAN-3,4-d₂ (TETRAHYDROFURAN)

El-Azhary, Adel Abbas

Abstract

The ir and Raman spectra of trans-dicyanocyclopropane and its 1,2-d₂ and 3,3-d₂ isotopomers were measured. The calculated ab initio force fields were scaled with respect to the experimental vibrational transitions. Empirical force fields were obtained from the scaled ones by varying selected force constants. The force fields were used for VCD calculations by the FPC, LMO and a priori methods. The measured VCD spectra were compared to the calculated results. Unlike the FPC and LMO results, the a priori results were very good compared to the experimental data.

Similarly, the ir and Raman spectra of THF-d₀, and d₈, d₄, trans-3,4-d₂ and cis-3,4-d₂ were measured. Using the C₂, C_s and C_2v geometries of THF, ab initio force fields were scaled with respect to the experimental vibrational transitions. The calculated absorption and VCD intensities were compared to the measured VCD spectra. Generally, calculated absorption and VCD intensities by the a priori method with the C₂ and C_2v geometries were in good agreement with the experimental results.