The tmQMg-L dataset includes 5210 monodentates that all have designated charge and coordinating atoms. We use the xyz2mol package to obtain mol objects for each monodentate ligand. Then, using the coordinating atom information from the dataset, we search for all monodentates where a carbon is the coordinating atom and where it has a charge of -1. This gives us a total of 327 anionic ligands with an anionic carbon as coordinating atom. This number is only an estimate as 223 monodentate ligands fail the xyz2mol procedure. Additionally there can be incorrect overall ligands charges in the dataset which adds additional error to the estimate. Nevertheless, anionic carbons are existing in experimentally verified TM-complexes and therefore supports our approach to use such coordinating ligands for the GA search.