A Rigid Cyclic (Alkyl)(amino)carbene Ligand Leads to Isolation of Low‐Coordinate Transition‐Metal Complexes

A protecting wall for low‐coordinate metal centers, reinforced by agostic interactions, is provided by a rigid cyclic (alkyl)(amino)carbene ligand (CAAC), as shown by the preparation of [RhCl(CO)(CAAC)] and [Pd(All)(CAAC)] + BF 4 − complexes (All=allyl). The former is related to the active species of Wilkinson's catalyst, and the latter is the first isolated cationic, formally 14‐electron Pd II species.