A Route to Stabilize Uranium(II) and Uranium(I) Synthons in Multimetallic Complexes.

Herein, we report the redox reactivity of a multimetallic uranium complex supported by triphenylsiloxide (−OSiPh3) ligands, where we show that low valent synthons can be stabilized via an unprecedented mechanism involving intramolecular ligand migration. The two‐ and three‐electron reduction of the oxo‐bridged diuranium(IV) complex [{(Ph3SiO)3(DME)U}2(μ‐O)], 4, yields the formal "UII/UIV", 5, and "UI/UIV", 6, complexes via ligand migration and formation of uranium‐arene δ‐bond interactions. Remarkably, complex 5 effects the two‐electron reductive coupling of pyridine affording complex 7, which demonstrates that the electron‐transfer is accompanied by ligand migration, restoring the original ligand arrangement found in 4. This work provides a new method for controlling the redox reactivity in molecular complexes of unstable, low‐valent metal centers, and can lead to the further development of f‐elements redox reactivity. [ABSTRACT FROM AUTHOR]