Incorporation of a Phosphino(pyridine) Subcomponent Enables the Formation of Cages with Homobimetallic and Heterobimetallic Vertices.

Biological systems employ multimetallic assemblies to achieve a range of functions. Here we demonstrate the preparation of metal-organic cages that contain either homobimetallic or heterobimetallic vertices. These vertices are constructed using 2-formyl-6-diphenylphosphinopyridine, which forms ligands that readily bridge between a pair of metal centers, thus enforcing the formation of bimetallic coordination motifs. Two pseudo-octahedral homometallic M I 12 L 4 cages (M I = Cu I or Ag I ) were prepared, with a head-to-head configuration of their vertices confirmed by X-ray crystallography and multinuclear NMR for Ag I . The phosphino-pyridine subcomponent also enabled the formation of a class of octanuclear Cd II 4 Cu I 4 L 4 tetrahedral cages, representing an initial example of self-assembled cages containing well-defined heterobimetallic vertices.