Exchange Interactions and Magnetic Properties of a Molecular Mn₁₈ -Ring Complex

Area of Science:

• Inorganic Chemistry
• Magnetochemistry
• Quantum Chemistry

Background:

• The synthesis of complex molecular structures with unique magnetic properties is a key area in inorganic chemistry.
• Manganese-oxygen clusters and their magnetic interactions are of significant interest for potential applications.

Purpose of the Study:

• To synthesize and characterize a novel compound featuring molecular Mn18-rings.
• To investigate the magnetic properties and exchange interactions within the Mn18-ring system.
• To explore the relationship between electronic structure and magnetic coupling using quantum-chemical methods.

Main Methods:

• Synthesis of the [Mn3O(OAc)7(HOAc)]6 · xAcOH compound.
• Magnetic susceptibility measurements across a range of temperatures and magnetic fields.
• Density Functional Theory (DFT) and ab-initio multi-reference (CASSCF/NEVPT2) calculations on model Mn3 complexes.

Main Results:

• The formation of a rare molecular Mn18-ring structure from Mn3 subunits bridged by acetate anions.
• Observation of weak ferromagnetic interactions between Mn3 units, which are suppressed in high magnetic fields.
• Correlation found between the orientation of pseudo-Jahn-Teller axes and exchange coupling energies in Mn3 models.
• Magnetic susceptibility data simulated by treating Mn3 units as largely uncoupled magnetic moments.

Conclusions:

• The synthesized Mn18-ring compound exhibits unique structural and magnetic characteristics.
• The weak inter-unit coupling allows for a simplified model of magnetic behavior within the ring.
• Computational methods provide insights into the electronic factors governing magnetic interactions in manganese clusters.