Unprecedented Seven- and Eight-Connected Lanthanide Coordination Networks

Area of Science:

• Materials Science
• Inorganic Chemistry
• Crystallography

Background:

• Coordination networks are crystalline materials constructed from metal ions and organic ligands.
• The connectivity of nodes in these networks dictates their structural properties and potential applications.
• Exploring new network topologies is crucial for advancing materials science.

Purpose of the Study:

• To synthesize and characterize novel coordination networks with high-connectivity nodes.
• To investigate the formation of eight- and seven-connected networks using 4,4-bipyridine-N,N′-dioxide (L) ligands.
• To explore the structural diversity achievable with lanthanide ions and specific ligands.

Main Methods:

• Single-crystal X-ray diffraction was used to determine the crystal structures.
• Lanthanide triflate and lanthanide mixed-anion salts were employed as precursors.
• The synthesis involved reacting metal salts with the 4,4-bipyridine-N,N′-dioxide ligand.

Main Results:

• The first examples of eight- and seven-connected coordination networks were successfully synthesized.
• [La(L)₄ ](CF₃ SO₃ )₃ formed an eight-connected body-centered hypercubic CsCl-like lattice.
• [La(L)₄ ](BPh₄ )(ClO₄ )₂ exhibited an unprecedented 4¹⁷ 6² topology with seven-connected nodes.

Conclusions:

• The use of 4,4-bipyridine-N,N′-dioxide ligands enables the construction of complex coordination networks with high node connectivity.
• The choice of counterions significantly influences the resulting network topology.
• These findings expand the library of known coordination network structures and topologies.