Related Experiment Video
Updated: Jul 2, 2026
08:55
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Spin-glass behaviour in the coordination polymer [Co(C3H3N2)2]n
Vinh Hung Tran1, Beata Swiatek-Tran
1Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw, Poland. v.h.tran@int.pan.wroc.pl
Dalton Transactions (Cambridge, England : 2003)
|September 4, 2008
Summary
The coordination polymer [Co(C3H3N2)2]n exhibits short-range antiferromagnetic behavior and a spin-glass-like state due to competing magnetic interactions. These findings were confirmed through magnetization and specific heat measurements.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Magnetism
Background:
- Coordination polymers are materials with diverse magnetic properties.
- Understanding magnetic interactions in low-dimensional systems is crucial for materials design.
Purpose of the Study:
- To investigate the magnetic behavior of the coordination polymer [Co(C3H3N2)2]n.
- To elucidate the nature of magnetic interactions and phase transitions in this material.
Main Methods:
- Magnetization measurements (low-field magnetic susceptibility, zero-field cooled, and field-cooled data).
- Specific heat measurements (magnetic specific heat, Cmag).
- Analysis using a spin S = 3/2 Heisenberg linear-chain model.
Main Results:
- Two magnetic susceptibility maxima observed around 8 K and 4 K (Tf), indicating short-range antiferromagnetic behavior and a spin-glass-like state.
- Magnetic irreversibility confirmed the spin-glass-like state.
- Absence of long-range order peaks in magnetic specific heat, with a broad maximum near Tf.
- Specific heat data below Tf followed Cmag(T)/T = gamma + AT.
- Schottky-type anomaly around 60 K due to crystal field splitting of Co2+ ions.
Conclusions:
- The observed spin-glass behavior arises from competing antiferromagnetic (AF) intra-chain and ferromagnetic (F) inter-chain interactions in a low-dimensional Co2+ ion arrangement.
- Susceptibility data analysis supports the presence of both F and AF interactions within a Heisenberg linear-chain model.
- The material displays complex magnetic phenomena characteristic of low-dimensional systems.
Related Concept Videos
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
01:17Spin–Spin Coupling: One-Bond Coupling
Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...
01:22Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive.
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
02:57Coordination Number and Geometry
For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to molecular geometry. The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and square planar.