Ultimately, these questions need to be settled by scientific consensus, taking the best available evidence from theory and experiments into account. The same applies to ON and ion charge or shell-filling assignments of complexes with essentially all metal ions, not just actinides. This means that discourse about these matters will remain an important part of chemistry. The case of PuO 2 is but one-albeit very interestingexample. Our study aims to provide an important step forward in the long quest to establish theoretical and experimental tools for actinide oxidation state assignments.