Metal-organic proximity in a synthetic pocket.

Proximity between a noninteractive organic substrate and a transition metal (trans-MCl2(PEt3)2; M = Pd or Pt) is achieved by their co-encapsulation within a synthetic cage, as revealed by X-ray crystallographic analysis and NOESY experiments. Through co-encapsulation with a Pd(II) complex, a terminal alkyne was activated within the cage to give a σ-alkynylpalladium complex.