Synthesis and Structure of Uranium Disilyl-Substituted Alkylidene Complexes.

Understanding the participation of f-orbitals of actinide elements in covalent bond formations is less explored, compared to the well-studied d-orbitals of transition metals, leading to the significant interest in actinide-carbon multiple bonds. Uranium alkylidene complex, containing an alkylidene linkage of the form U═CR (R = H, alkyl, silyl), represents a key milestone in actinide-ligand multiple bonding, but their isolation and characterization have remained elusive. Herein, we present the synthesis of an unprecedented uranium disilyl-substituted alkylidene complex, achieved through sequential dehydrogenation reactions of a methyl group under mild conditions. Single-crystal X-ray diffraction reveals the U═C double bond length of 2.332(4) Å. Quantum chemical calculations suggest that both 5f and 6d orbitals of uranium play a key role in the U═C double bond formation.