This dataset probes chemical reactions of methyl halides with halide anions, i.e. X- + CH3Y -> CH3X + Y-, and contains structures for all possible combinations of X,Y = F, Cl, Br, I. The dataset also includes various structures for several smaller molecules that can be formed in fragmentation reactions, such as CH3X, HX, CHX or CH2X- as well as geometries for H2, CH2, CH3+ and XY interhalogen compounds. In total, the dataset provides reference energies, forces, and dipole moments for 452709 structures calculated at the DSD-BLYP-D3(BJ)/def2-TZVP level of theory [1-4] using the ORCA 4.0.1 code [5,6]. For more details, see https://arxiv.org/abs/1902.08408. [1] Grimme, S.; Antony, J.; Ehrlich, S. and Krieg, H. J. Chem. Phys. 132, 154104 (2010). [2] Kozuch, S.; Gruzman, D. and Martin, J. M. J. Phys. Chem. C 114, 20801-20808 (2010). [3] Grimme, S.; Ehrlich, S. and Goerigk, L. J. Comput. Chem. 32, 1456-1465 (2011). [4] Weigend, F. and Ahlrichs, R. Phys. Chem. Chem. Phys. 7, 3297-3305 (2005). [5] Neese, F. Wiley Interdiscip. Rev. Comput. Mol. Sci. 2, 73-78 (2012). [6] Neese, F. Wiley Interdiscip. Rev. Comput. Mol. Sci. 8, e1327 (2018).