Modulation of Benzene or Naphthalene Binding to Palladium Cluster Sites by the Backside-Ligand Effect

Thiophene and Selenophene Binding at a Pd3 Cluster Site

We report the triply bridging coordination of thiophene and selenophene to a trinuclear metal cluster site. The triply bridging coordination of selenophene at a Pd₃ site forms a unique spiro-type Pd₅ cluster. Furthermore, either thiophene or selenophene is accommodated stably at a Pd₃ site supported by a backside μ₃ -cyclooctatetraene ligand through the face-capping μ₃ -coordination. The Pd₃ site supported by the cyclooctatetraene ligand showed higher binding affinity of benzene over thiophene, although a Pd₂ site strongly favors thiophene over benzene.

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 [Pd₄ (μ₄ -C₈ H₈ )(μ₄ -C₉ H₉ )]⁺ , in which the ligand-based metal capacity is full in terms of the usage of all C=C moieties of the smaller carbocyclic ligand C₈ H₈ in coordination, can accommodate extra M⁰ {P(OPh)₃ }₂ (M=Pd, Pt) moieties without coordinative assistance by either the C₉ H₉ or the C₈ H₈ ligand.