AbstractSeven different density functionals, including GGAs, meta-GGAs, hybrids and range-separated hybrids, and considering Grimme’s empirical dispersion correction (M06-L, M06-2X, PBE0, B3LYP, B3LYP-D3, CAM-B3LYP, ωB97X) have been tested for their performance in the prediction of molecular structures, energies and energy barriers for a class of newly developed antitumor platinum complexes involving main group heavy elements such as arsenic. The calculated structural parameters, energies and energy barriers have been compared to the available experimental data. The results show that range-separated hybrid functionals CAM-B3LYP and ωB97X give good results in predicting both geometrical parameters and isomerization energies and barrier heights and are promising new tools for the theoretical study of novel platinum(II) arsenic compounds.