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Field-Induced Slow Magnetic Relaxation in Pentacoordinate Co(II) Complexes: Tuning Magnetic Anisotropy Through Halide
Hong-Yao Guo1, Wei-Quan Lin1, Ji-Dong Leng1
1School of Chemistry and Chemical Engineering/Institute of Clean Energy and Materials, Guangzhou Higher Education Mega Center, Guangzhou University, No. 230 Wai Huan Xi Road, Guangzhou 510006, China.
Researchers synthesized and studied three cobalt(II) complexes with unique magnetic properties. These pentacoordinate complexes exhibit slow magnetic relaxation, influenced by halide ligand electronegativity.
Area of Science:
- Coordination Chemistry
- Magnetochemistry
- Materials Science
Background:
- Pentacoordinate cobalt(II) complexes are of interest for their diverse magnetic behaviors.
- The bidentate phosphine ligand 1,2-bis(diphenylphosphino)benzene (dppb) can stabilize various coordination geometries.
- Halide ligands play a crucial role in modulating the electronic and magnetic properties of metal complexes.
Purpose of the Study:
- To synthesize and characterize novel pentacoordinate cobalt(II) complexes.
- To investigate the structural and magnetic properties of these complexes.
- To understand the influence of halide ligands on magnetic anisotropy and relaxation dynamics.
Main Methods:
- Synthesis of three pentacoordinate cobalt(II) complexes: [CoX(dppb)2]X (X = Cl, Br, I).
- Single-crystal X-ray diffraction for structural determination.
- Magnetic susceptibility and relaxation measurements to probe magnetic properties.
Main Results:
- All three complexes adopt vacant octahedron (C4v) geometries with halide ligands in axial positions.
- Complexes exhibit field-induced slow magnetic relaxation.
- Positive D values indicate significant magnetic anisotropy, decreasing with decreasing halide electronegativity (25.3(2) cm⁻¹ for Cl, 21.6(1) cm⁻¹ for Br, 19.4(2) cm⁻¹ for I).
- Raman processes dominate magnetic relaxation at higher temperatures.
Conclusions:
- The synthesized cobalt(II) complexes display characteristic slow magnetic relaxation behaviors.
- Magnetic anisotropy and relaxation dynamics are systematically influenced by the nature of the halide ligand.
- These findings contribute to the understanding of single-molecule magnet behavior in coordination complexes.
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