While the d⁰ transition-metal POMs of Group V (V⁵⁺, Nb⁵⁺, Ta⁵⁺) and Group VI (Mo⁶⁺, W⁶⁺) have been known for more than a century, the actinyl peroxide POMs, specifically those built of uranyl triperoxide or uranyl dihydroxidediperoxide polyhedra, were only realized within the last decade. While virtually every metal on...