Magnetic Properties of Coordination Compounds

The capacity of transition metals to create magnets is a notable property. The coordination compound complexes show magnetic properties. Unpaired electrons in coordination metal complexes make them magnetic in nature. This magnetism must be owing to the presence of unpaired d electrons because the final electrons are in the d orbitals. The electronic spin generates magnetism and the number of unpaired electrons in a molecule determines its magnetic properties. A magnetic field is produced by the movement of magnetic or electric charges. These magnetic field lines of force have certain definite properties. The magnetism shown by the complexes is mainly three types: ferromagnetism, paramagnetism and diamagnetism. 

The quantum number ms represents the spin of a single electron as +(12 )or –(12 ). When an electron is linked with another, its spin is negated, but when the electron is unpaired, it forms a weak magnetic field. The paramagnetic effects are amplified when there are more unpaired electrons. The repulsive forces between electrons in the ligands and electrons in the compound cause the electron configuration of a transition metal (d-block) to change in a coordination compound. The chemical may be paramagnetic or diamagnetic, depending on the strength of the ligand.

The magnetic moment of a system containing unpaired electrons is proportional to the number of unpaired electrons: the stronger the magnetic moment, the more unpaired electrons there are. The force that a substance feels in a magnetic field is measured by magnetic susceptibility.

Properties of magnet

• The magnet attracts ferromagnetic materials (iron)
• Magnetic poles exist in pairs in magnets, and each magnet has two magnetic poles, N pole and S pole
• On suspending a magnet freely, it always comes in the north-south direction
• When two magnets are in close proximity, the same magnetic poles repel and push away from one other, whereas different magnetic poles attract and stick to each other
• As a result, the same poles repel each other while the opposite poles attract

Properties of Magnetic Lines of Force  

• Each line is a continuous and closed curve
• The magnetic lines of force start from the north pole of the magnet and end at the south pole
• These lines will never come into contact with one another
• They are densely packed near the poles, where the magnetic field is particularly intense
• They have an effect on the needle of the magnetic compass

Ferromagnetism or Permanent Magnets

 The fundamental mechanism by which certain materials (such as iron) produce permanent magnets is ferromagnetism. This indicates the material has persistent magnetic properties rather than merely expressing them when exposed to a magnetic field from the outside. The electrons of atoms in a ferromagnetic element are organised into domains, each with the same charge. These domains align in the presence of a magnetic field, resulting in parallel charges over the entire complex. The number of unpaired electrons and the atomic size of a chemical determine whether it is ferromagnetic or not.

Paramagnetism – Attracted to the Magnetic Field

The magnetic condition of an atom having one or more unpaired electrons is known as paramagnetism. Due to the electrons’ magnetic dipole moments, the magnetic field attracts the unpaired electrons. Before any orbital is to be twice occupied, according to Hund’s Rule, electrons must occupy it singly. This results in a higher number of unpaired electrons in the atom. Unpaired electrons have magnetic properties in both directions because they can spin in either way. Magnetic fields attract paramagnetic atoms because of this ability. O2, or diatomic oxygen, is an excellent example of paramagnetism (described using the molecular orbital theory).

Diamagnetism – Repelled by the Magnetic Field

The magnet has no effect on molecular nitrogen (N2) since it has no unpaired electrons and is diamagnetic. The presence of paired electrons, i.e., no unpaired electrons, distinguishes diamagnetic compounds. The electron spins are oriented in different directions according to the Pauli Exclusion Principle, which stipulates that no two electrons may occupy the same quantum state at the same moment. As a result, the magnetic fields of the electrons cancel out, leaving no net magnetic moment and preventing the atom from being attracted to a magnetic field.

How to Find Out the Magnetic Nature (Paramagnetic or Diamagnetic) of a Complex?

The electron configuration of a substance can be used to identify its magnetic properties: the substance is paramagnetic if its electrons are unpaired, and it is diamagnetic if all of its electrons are paired. The three steps required are:

1. Write the electronic configuration.
2. Make a diagram of the valence orbitals.
3. Determine whether the substance is paramagnetic or diamagnetic by looking for unpaired electrons.

Conclusion 

The coordination metal complexes exhibit magnetic nature due to the presence of electrons in the d orbital, either paired or unpaired. Magnetism is mainly of three types: paramagnetism, diamagnetism and ferromagnetism. Paramagnetism is caused due to the presence of unpaired electrons in the d orbital and diamagnetism results due to the fully paired electron in d orbitals. Ferromagnetism is exhibited by metal complexes that can retain their magnetism for a longer time once magnetised. There are some properties that a magnet exhibits, like the same poles will repel and the unlike poles will show an attraction, and when the magnet is suspended, it will always align in the N-S direction.