After obtaining accurate and stable ACE MLPs for the reaction of CP and MVK in two solvent environments, we utilised these potentials to investigate the reaction pathway in more detail. This was done by conducting a relaxed 2D scan along the forming C-C bonds r 1 and r 2 in both implicit and explicit solvents (Fig. and Fig. , respectively). Analysis of the endo 2D scan in both implicit and explicit water reveals the presence of a zwitterionic-like structure characterised by the formation of only one C-C bond in the region around r 1 < 1.6 Å and 2.5 < r 2 < 3.0 Å (an example marked by a cross in Fig. ). Unrestricted DFT calculations on these geometries confirmed that they do not exhibit any diradical character (SI § S8). The cross-labelled zwitterionic species is slightly more stabilised in the explicit solvent than in implicit solvent (∆∆E = 2.2 kcal mol -1 ).