Comment on the assignments of some vibrational bands of oxalyl fluoride

In view of existing contradictory assignments of the symmetrical stretching vibrations associated with the formal C–C and C–F bonds of trans/ cis oxalyl fluoride, an additional theoretical analysis of the corresponding calculated wavenumbers was preformed on trans-C 2O 2F 2 and cis-C 2O 2F 2 based on previously calculated ab initio scaled force fields at the HF/6-31G computational level and new force fields calculated at the MP2/aug-cc-pVTZ level. This novel analysis included computational data from the isotopic shifts brought about by incorporating 13C and 14C atoms into the structure. A detailed examination of the calculated wavenumbers made it possible to validate the assignments of the ν 2 and ν 3 wavenumbers in the trans-C 2O 2F 2 and cis-C 2O 2F 2 molecules as the formal C–C bond stretching and the formal C–F bond symmetrical stretching vibrations, respectively.