# Unusual bonding situations in Th(iv) and U(iv)–Al(iii) pnictogen complexes

**Authors:** Pritam Mahawar, Ganping Wang, Robert J. Ward, Steven P. Kelley, Laurent Maron, Justin R. Walensky

PMC · DOI: 10.1039/d5sc09143h · Chemical Science · 2026-03-18

## Abstract

To enhance our understanding of the electronic structure of early actinides, a synthetic methodology of using an Al(i) precursor, [(C5Me5)Al]4, was applied to both thorium and uranium dipnictido complexes. The cleavage of the E–E bond in dipnictido actinide complexes, [(C5Me5)2An(η2-E2R2)], An = Th, U; E = N, P, As; R = Ph or 2,4,6-Me3C6H2 (Mes), with 0.25 equivalents of [Al(C5Me5)]4, yields the heterobimetallic complexes, [(C5Me5)2An(µ2-ER)2Al(C5Me5)]. In the case of An = U, E = N, the U(vi) bis(imido) complex, [(C5Me5)2U(=NPh)2], is reduced by [(C5Me5)Al]. Based on the solid-state structures and DFT calculations, including Nucleus Independent Chemical Shift (NICS), all six complexes show aromaticity within the An–E–Al–E moiety. For Th, only σ-aromaticity is observed, but both σ + π aromaticity is observed in the U complexes.

To enhance our understanding of the electronic structure of early actinides, a synthetic methodology of using an Al(i) precursor, [(C5Me5)Al]4, was applied to both thorium and uranium dipnictido complexes.

## Full-text entities

- **Chemicals:** actinides (MESH:D008671), As (MESH:D001151), U (MESH:D014501), (C5Me5)Al (-), P (MESH:D010758), Al (MESH:D000535), N (MESH:D009584), Mes (MESH:C004550), Th (MESH:D013910), E (MESH:D004540)

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Source: https://tomesphere.com/paper/PMC12997793