Experimental XIAM and Pickett Fits, Kraitchman structure and semi-experimental as well as mass dependent structure fits for citraconic and itaconic anhydride

We provide the experimental fit files obtained with the XIAM (V2.5e) program of H. Hartwig and H. Dreizler for citraconic anhydride as well as those for itaconic anhydride obtained with the SPFIT program of H.M. Pickett. In addition, the Kraitchman, semi-experimental equilibrium (reSE) and mass dependent structures (rm(1) and rm(2)) have been deposited. The former has been computed with Z. Kisiel's KRA program (version 4a.IV.2017) while the latter two have been obtained with his STRFIT (version 14.VI.2021) program. The listed programs can be downloaded from Z. Kisiel's PROSPE website All necessary files to redo any fit are provided. The experimental fits are sorted according to 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 anhydrided. The reSE, rm(1) and rm(2) structure fits have been carried based on 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 calculations with the Gaussian 16 (Rev. C.01) program package. In all cases, the aug-cc-pVTZ basis set was used. All files provided are in an ASCII format and can be opened with any text editor.