Incorporation of a Phosphino(pyridine) Subcomponent Enables theFormation of Cages with Homobimetallic and Heterobimetallic Vertices

Biological systems employ multimetallic assemblies to achieve a range of functions. Here we demonstrate thepreparation of metal-organic cages that contain either homobimetallic or heterobimetallic vertices. These vertices are constructedusing 2-formyl-6-diphenylphosphinopyridine, which forms ligands that readily bridge between a pair of metal centers, thus enforcingthe formation of bimetallic coordination motifs. Two pseudo-octahedral homometallic MI12L4cages (MI=CuIor AgI) wereprepared, with a head-to-head configuration of their vertices confirmed by X-ray crystallography and multinuclear NMR for AgI. Thephosphino-pyridine subcomponent also enabled the formation of a class of octanuclear CdII4CuI4L4tetrahedral cages, representingan initial example of self-assembled cages containing well-defined heterobimetallic vertices.