Supramolecular squares of dirhodium(II) tetracarboxylate: combining carboxylate-exchange and metal-ligand coordination for self-assembly.

Square self-assemblies are obtained from dirhodium(II) tetracarboxylate complexes using an isonicotinate-type ligand to act as an equatorial ligand to one dirhodium unit and an axial ligand to another. It is shown that the supramolecular squares are formed selectively out of a number of possible compounds in the dynamic carboxylate exchange library.