Field-induced non-linear magnetic responses of all-metal Jellium σ-aromats

In recent times all-metal aromaticity has arisen, challenging classical views of aromaticity. All-metal aromaticity invokes metal-metal bonding, but this remains rare for the actinides. Recently, one-electron trithorium superatom clusters exhibiting exalted diamagnetism and hence open-shell Jellium aromaticity have been reported. Those clusters complement closed-shell two-electron congeners, but computational assessments advanced conflicting interpretations. Here, we report one- and two-electron trithorium clusters that all exhibit exalted diamagnetism, demonstrating open- and closed-shell Jellium aromaticities. We show that these Jellium aromats exhibit non-linear magnetic responses, so a foundational assumption of ring current calculations is not met, accounting for the experimental-computational disagreement. This work suggests that while π-aromaticity results from preorganized coherent wave functions, for σ-aromats there may be an electronic reorganization barrier to cohesive wave functions and Jellium aromatic ring currents. This work demonstrates the importance of caution when using ring current calculations to assign aromatic character if the experimental magnetic response is not understood.