Cyclic [Cu-biRadical]₂ Secondary Building Unit in 2p-3d and 2p-3d-4f Complexes: Crystal Structure and Magnetic...

Area of Science:

• Coordination Chemistry
• Materials Science
• Magnetochemistry

Background:

• Development of novel ligands is crucial for designing advanced molecular materials.
• Nitronyl nitroxide biradicals are valuable building blocks for magnetic coordination compounds.
• 2p-3d-4f heterometallic complexes offer tunable magnetic properties.

Purpose of the Study:

• To synthesize and characterize a new nitronyl nitroxide biradical ligand, biNIT-3Py-5-Ph.
• To prepare a discrete 16-spin Cu-radical complex and 1D coordination polymers involving lanthanides.
• To investigate the magnetic properties arising from the interplay of copper, lanthanide, and radical centers.

Main Methods:

• Synthesis of the biNIT-3Py-5-Ph ligand and subsequent metal complexes.
• X-ray crystallographic analysis to determine the structural motifs ([Cu-biNIT]2 units, discrete complex, 1D polymer).
• Magnetic susceptibility measurements to probe magnetic interactions (ferromagnetic, antiferromagnetic) and relaxation dynamics.

Main Results:

• Successful synthesis of [Cu8(biNIT-3Py-5Ph)4(hfac)16] (1) and {[Ln(hfac)3][Cu(hfac)2]2(biNIT-3Py-5Ph)2}n (Ln = Gd, Tb, Dy) (2-4).
• X-ray analysis revealed a common cyclic [Cu-biNIT]2 secondary building unit in all complexes.
• Magnetic studies indicated a combination of ferromagnetic and antiferromagnetic interactions; no slow magnetic relaxation was observed for Tb and Dy complexes.

Conclusions:

• The novel biNIT-3Py-5Ph ligand effectively bridges copper and lanthanide ions, forming complex magnetic architectures.
• The coordination environment dictates the interplay of magnetic exchange interactions within the complexes.
• These radical-bridged coordination polymers do not exhibit single-molecule magnet behavior under the studied conditions.