The Ketimide Ligand is Not Just an Inert Spectator: Heteroallene Insertion Reactivity of an Actinide–Ketimide Linkage in a Thorium Carbene Amide Ketimide Complex

摘要

The ketimide anion R2C—N⁻ is an important class of chemically robust ligand that binds strongly to metal ions and is considered ideal for supporting reactive metal fragments due to its inert spectator nature; this contrasts with R2N⁻ amides that exhibit a wide range of reactivities. Here, we report the synthesis and characterization of a rare example of an actinide ketimide complex [Th(BIPM^TMS){N(SiMe3)2}(N—CPh2)] [>2, BIPM^TMS=C(PPh2NSiMe3)2]. Complex >2 contains Th—Ccarbene, Th—Namide and Th—Nketimide linkages, thereby presenting the opportunity to probe the preferential reactivity of these linkages. Importantly, reactivity studies of >2 with unsaturated substrates shows that insertion reactions occur preferentially at the Th—Nketimide bond rather than at the Th—Ccarbene or Th—Namide bonds. This overturns the established view that metal-ketimide linkages are purely inert spectators.