Substrate Binding by a Parallel Metal Sheet Sandwich Complex: A Unique Role of an Additional Metal Atom

A unique metal addition to the edge of a triangular palladium sandwich cluster is reported. While the edge coordination sites of a parallel sandwich complex are narrow because of two sterically encumbering π‐ligands, association of an additional metal atom to a metal sheet gives a wider coordination site. It was proved that the additional metal atom plays a crucial role in binding of cyclopentadienyl by a Pd₃ sheet sandwich complex.