Exceeding Metal Capacity in Sandwich Complexes: Ligand‐Unsupported Docking of Extra Metal Moieties at Edges of a Metal Sheet Sandwich Complex

The ligand‐unsupported accommodation of extra metal moieties in a sandwich complex is reported. Although it has been considered that the metal‐capacity of a metal sheet sandwich complex is strictly limited by the size of cyclic unsaturated hydrocarbon ligands, the M−M edge bonds in a metal sheet sandwich complex provide a ligand‐unsupported docking site for extra metal moieties, allowing expansion of metal‐capacity in sandwich complexes. The metal sheet sandwich complex [Pd 4 (μ 4 ‐C 8 H 8 )(μ 4 ‐C 9 H 9 )] + , in which the ligand‐based metal capacity is full in terms of the usage of all C=C moieties of the smaller carbocyclic ligand C 8 H 8 in coordination, can accommodate extra M 0 {P(OPh) 3 } 2 (M=Pd, Pt) moieties without coordinative assistance by either the C 9 H 9 or the C 8 H 8 ligand.