Synthesis and Isolation of Thorium Dinitrogen Complexes: 5f Orbital Matters

Thorium-dinitrogen complexes, long proposed as critical intermediates for actinide-mediated dinitrogen activation and bond cleavage, have not been isolated. In this work, three heterobimetallic [Cr]-N₂-[Th] complexes featuring a Th-N₂ moiety were synthesized via a metathesis reaction between a chromium(0) dinitrogen precursor and Th(IV) chloride derivatives. X-ray crystallographic analysis unambiguously confirmed their heterobimetallic [Cr]-N₂-[Th] bridging geometry. Density functional theory (DFT) calculations revealed non-negligible 5f orbital contributions to the Th-N bonding interactions.