Normal coordinate analysis and spectral band assignments of the normal vibrations of deutrated acetate anion

Abstract

Results of the normal coordinate analysis on the CD₃CO₂^- ion suggest a revision of previous assignments of some of its infrared absorption bands. Thus, the empirical suggestion of accidental degeneracy amongst CD₃ stretching modes is not supported by our calculations and, accordingly, the bands at 2183 and 2167 cm^-1 are due to V_s(CD₃) and V_as(CD₃), respectively, and not V_as(COO) + V(COO) and 2d_s⁺(CD₃) combination and overtone bands. Also, the bands at 880 and 928 cm-1 formerly assigned to pure C-C stretching and CD₃ rocking modes are now rs(CD₃) coupled with Vs(CD₃) and Vs(CD₃),  and V(C-C) coupled with s(COO) and s(CD3) modes, respectively.