A Ruthenium–Iron Bimetallic Supramolecular Cage with <i>D</i><sub>4</sub> Symmetry from a Tetrapyridyl Iron(I) Metalloligand

The novel iron­(I) sandwich compound [Cp*Fe­(η<sup>4</sup>-C<sub>4</sub>Py<sub>4</sub>)] (<b>1</b>) was prepared and characterized by various methods, including X-ray crystallography. Coordination-driven self-assembly of a diruthenium acceptor with the tetrapyridyl metalloligand [Cp*Fe­(I)­(η<sup>4</sup>-C<sub>4</sub>Py<sub>4</sub>)] led to a <i>D</i><sub>4</sub>-symmetric three-dimensional M<sub>4</sub>L<sub>2</sub> tetragonal supramolecular cage. This cage was characterized by IR and high-resolution electrospray ionization mass spectrometry. Its solid-state structure was confirmed by X-ray crystallography, showing a novel <i>D</i><sub>4</sub> cage system.