Stellated polyhedral assembly of a topologically complicated Pd4L4 ‘Solomon cube’

Metallosupramolecular chemistry relies on self-assembly processes in which complicated species form through labile dative-covalent interactions. Two remarkable areas of this chemistry are the synthesis of topologically complicated threaded assemblies and of three-dimensional (3D) polyhedral assemblies. Very few polyhedral 3D metallosupramolecular assemblies show threaded motifs within them. Here we report an example of a new type of threaded 3D metallosupramolecular assembly built from four organic ligands and four palladium ions, a Pd4L4 so-called 'Solomon's cube' in which interweaving and twisting of the ligands form both Solomon's links and figure-of-eight ring motifs. In the solid state, six of these Pd4L4 tetramers assemble into a hollow spheroid that closely resembles a stellated truncated hexahedron.