High-pressure calculations. High pressure calculations were performed using the XP-PCM method at the ωB97XD/def2-ΤZVP level of theory in Gaussian 16 and an in-house Julia script. The XP-PCM is a quantum chemical method aimed to introduce the effects of the pressure on the calculation of the electronic energy 𝐺 /0 of a molecular system in a dense medium via a Pauli exchange-repulsion interaction between the molecular system and the external medium. Such a Pauli-exchange repulsion is motivated by the fact that at high pressure, the reduction of the volume of a dense medium forces the intermolecular distances below the van der Waals contacts, in a domain where the intermolecular interactions are dominated by the Pauli exchange-repulsion. The increase of the pressure is modeled by simply shrinking the volume 𝑉 1 of the cavity hosting the molecular system so as to increase the overlap between the electron densities of the system and of the external medium (Figure ). This molecular cavity is built up starting from the envelope of vdW spheres centered on the nuclei of the reactive system and with scaled vdW radii. In studying chemical reactions at high pressure, the effective potential energy for the motion of the nuclei of the reactive system, 𝐺 232 (𝑝), corresponds to the electronic energy 𝐺 /0 (𝑝), supplemented by a contribution of the so-called cavitation Gibbs energy that corresponds to the work necessary to create the void cavity hosting the molecular solute at the given condition of pressure 𝑝: