Abstract
Abstract
Since their discovery in 1973, transition metal Fischer carbynes have become a foundational class of metal–carbon triple bond in organometallic chemistry. However, even though the uranium Fischer carbyne bonding motif has been a fundamental target in
f
-element chemistry, its isolation has remained challenging. Here we report the synthesis and characterization of the uranium Fischer-type carbyne complex [N″
3
U(μ-CNN)UN″
3
] (N″ = N(SiMe
3
)
2
). Single-crystal X-ray diffraction analysis reveals a uranium–carbyne distance of 2.379(15) Å, and density functional theory calculations combined with experimental quantum crystallography Hirshfeld atom refinement reveal the presence of two-electron C→U
σ
-donation, weak two-electron C→U
π
-donations and two orthogonal one-electron U→C
π
-back-bonds, demonstrating
σ
2
π
1
π
1
Fischer-type carbyne bonding overall. This work redefines the range of bonding modes for the diazomethanediide ligand and reveals a uranium–carbon triple-bond interaction that is related, yet distinct from transition metal Fischer carbynes, providing a basis to develop and understand
f
-element carbyne chemistry.