A Ruthenium–Iron Bimetallic Supramolecular Cage with D₄ Symmetry from a Tetrapyridyl Iron(I) Metalloligand

The novel iron­(I) sandwich compound [Cp*Fe­(η⁴-C₄Py₄)] (1) 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)­(η⁴-C₄Py₄)] led to a D₄-symmetric three-dimensional M₄L₂ 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 D₄ cage system.