We set-up a QM/MM model [Cu(C8PhenMe6)I] catalyst, where the reaction centre is modelled by QM and the macrocyclic ligand as well as the solvent by MM (see Methods and SI Figure and Table for details). We obtained 152 QM/MM MD reaction trajectories for the C-N coupling step of the with a total of over 3 ns of simulation time. Out of these, 142 reacted within 20 ps of simulation time. From these trajectories we evaluated the reaction energy and labelled the structural data accordingly as educt, transition state, or product -resulting in three ensembles. We then used this information to identify the reaction coordinate, identify a sequence of movements leading to the reaction, and quantify it.