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.