Computational outputs of DFT, MP2 and Coupled Cluster calculations for geometry optimizations and frequency calculations

We provide the computational output files of all calculations needed for the structure determination as well as high level coupled cluster reference calculations. For the B3LYP-D3(BJ), PBE0-D3(BJ), CAM-B3LYP-D3(BJ), LC-ωPBE-D3(BJ), M06-2X, B2PLYP-D3(BJ), DSD-PBEP86-D3(BJ) and MP2 methods, this includes vibrational perturbation theory calculations of second order (VPT2) for the parent (all isotopes in their naturally most abundant form), singly 13C substituted and singly 18O substituted species. 18O data is only available for citraconic anhydride. These calculations have ben carried out with Gaussian 16 (Rev. C.01).