Trigonally Distorted Hexacoordinate Co(II) Single-Ion Magnets.

Area of Science:

• Coordination Chemistry
• Magnetochemistry
• Materials Science

Background:

• Development of single-ion magnets (SIMs) is crucial for advancing molecular magnetism and quantum computing.
• Cobalt(II) complexes are promising candidates for SIMs due to their tunable electronic structures and magnetic properties.
• Carboxylate ligands and nitrogen-based chelating ligands offer versatile coordination environments for metal ions.

Purpose of the Study:

• To synthesize and characterize novel cobalt(II) carboxylate complexes incorporating the neocuproine ligand.
• To investigate the structural, magnetic, and relaxation properties of these synthesized complexes.
• To explore their potential as single-ion magnets.

Main Methods:

• Simple chemical reactions to synthesize three cobalt(II) carboxylate complexes: [Co(neo)(RCOO)₂] where R = -CH₃ (1), (CH₃)₃C- (2), and 4OH-C₄H₆- (3).
• X-ray crystallography to determine the molecular structures and coordination environments.
• Combined theoretical and experimental magnetic property investigations using L-S Hamiltonian formalism and AC susceptibility measurements.

Main Results:

• Successfully synthesized three distinct cobalt(II) carboxylate complexes with neocuproine.
• Crystal structures reveal distorted coordination geometries, with varying degrees of trigonal distortion.
• Compounds exhibit large magnetic anisotropies and demonstrate slow relaxation of magnetization, classifying them as field-induced single-ion magnets.
• Complex 1 shows a unique weak AC signal even in the absence of an external magnetic field.

Conclusions:

• The synthesized cobalt(II) complexes are effective single-ion magnets.
• The L-S Hamiltonian is essential for accurately describing their magnetic anisotropy.
• Complex 1 displays intriguing magnetic behavior at zero field, warranting further investigation.