Force field calculations for ethanedial, butanedione and some cyclic 1,2-diketones with respect to the influence of the intercarbonyl dihedral angle on their vibrational frequencies

Abstract The molecular vibrations of ethanedial, butanedione and some cyclic 1,2-diketones are calculated by means of normal coordinate analyses. Starting from published ab initio force constants, Simplex-optimized force fields are developed. Using these force fields, all vibrational frequencies of ethanedial and the carbonyl stretching vibrations of the cyclic 1,2-diketones are calculated for different intercarbonyl dihedral angles.