A Mn(iii) single ion magnet with tridentate Schiff-base ligands

Area of Science:

• Coordination Chemistry
• Magnetochemistry
• Materials Science

Background:

• Single-ion magnets (SIMs) are molecular materials that exhibit slow magnetic relaxation, crucial for applications in quantum computing and data storage.
• Manganese(III) complexes are actively researched for SIM properties due to their accessible electronic configurations and potential for high magnetic anisotropy.
• Schiff-base ligands offer versatile coordination environments that can tune the magnetic properties of metal ions.

Purpose of the Study:

• To synthesize and characterize a mononuclear manganese(III) complex with tridentate Schiff-base ligands.
• To investigate the magnetic properties, specifically the single-ion magnet behavior and zero-field splitting (D).
• To determine the energy barrier for spin reversal and relaxation times for potential applications.

Main Methods:

• Synthesis of a mononuclear Mn(III) complex featuring tridentate Schiff-base ligands.
• Magnetic measurements, including AC susceptibility and DC magnetization, to assess magnetic behavior.
• High-frequency electron paramagnetic resonance (HF-EPR) spectroscopy to precisely determine axial zero-field splitting parameters (D).
• Computational studies (e.g., DFT) to analyze electronic structure and validate experimental findings.

Main Results:

• The mononuclear Mn(III) complex exhibits single-ion magnet behavior with a significant negative axial zero-field splitting (D = -4.73 cm⁻¹).
• HF-EPR revealed two distinct large axial D values for the two crystallographically independent Mn(III) cations (D = -4.60 cm⁻¹ and D = -4.18 cm⁻¹).
• The complex demonstrates the largest D value reported to date for a Mn(III) SIM, with an energy barrier for spin reversal of 10.19 K and a relaxation time of 1.476 × 10⁻⁶ s at 2000 Oe.

Conclusions:

• The synthesized Mn(III) complex represents a new benchmark for Mn(III) single-ion magnets due to its exceptionally large zero-field splitting.
• The observed properties, including the high energy barrier and short relaxation time, highlight the potential of this complex for molecular magnetism applications.
• Computational analysis successfully elucidated the electronic structure, confirming the origin of the significant zero-field splitting.