[Pd(MeCN) 4 ] 2+ •MeCN complex in clusters of 20 -30 MeCN molecules The structures used as starting conformations in the multi-step AL approach described in this section have been generated with CREST. The TS and RS structures obtained in the gas phase (from the dataset (i)) were solvated by 20 to 30 MeCN molecules using the QCG method and the lowest energy conformation of the cluster was selected with CREST, as mentioned above. Different conformations were generated for the different AL training phases as follows. Firstly, the data set (i) was used as an initial data set in the AL loop, starting from TS solvated by 20 MeCN molecules; new structures were selected using the similarity selector with a threshold of 0.9999, with a maximum MD simulation time set to 750 fs, the time found to be required for transitioning from trigonal bipyramidal to squarepyramidal coordination geometries, observed from previous trials. This AL phase yielded 56 structures.