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))fN(SiMe3)J(N= CPh2)][2, BIPM~(TMS) = C(PPh2NSiMe3)2]. Complex 2 contains Th=C_(carbene) Th-N_(amide) and Th~N_(ketimide) 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—N_(ketimide) bond rather than at the Th= C_(carbene) Th—N_(amide) bonds. This overturns the established view that metal-ketimide linkages are purely inert spectators.