σ‐Cyclopropyl to π‐Allyl Rearrangement at AuIII

The possibility for AuIII σ‐cyclopropyl complexes to undergo ring‐opening and give π‐allyl complexes was interrogated. The transformation was first evidenced within (P,C)‐cyclometalated complexes, it occurs within hours at −50 °C. It was then generalized to other ancillary ligands. With (N,C)‐cyclometalated complexes, the rearrangement occurs at room temperature while it proceeds already at −80 °C with a dicationic (P,N)‐chelated complex. Density Functional Theory (DFT) calculations shed light on the mechanism of the transformation, a disrotatory electrocyclic ring‐opening. Intrinsic Bond Orbital (IBO) analysis along the reaction profile shows the cleavage of the distal σ(CC) bond to give a π‐bonded allyl moiety. Careful inspection of the structure and bonding of cationic σ‐cyclopropyl complexes support the possible existence of C−C agostic interactions at AuIII. (P,C)/(N,C)‐cyclometalated as well as (P,N)‐chelated AuIII σ‐cyclopropyl complexes readily undergo ring‐opening to give the corresponding π‐allyl complexes by cleavage of the distal σ(C−C) bond. The possible existence of σ(C−C) agostic interactions at AuIII is supported computationally.