Low Spin Complex
Definition and meaning of Low Spin Complex in chemistry.
A low spin complex is a coordination compound in which the transition metal's d-electrons are paired up in the lower energy orbitals rather than occupying higher energy orbitals. This specific electron configuration occurs when the crystal field splitting energy is significantly greater than the electron pairing energy.
In more detail
According to crystal field theory, when ligands approach a central transition metal ion, they cause the degenerate d-orbitals to split into different energy levels. Strong-field ligands, such as cyanide or carbon monoxide, create a remarkably large energy gap between these split orbitals. Because it requires less energy to pair electrons in the lower energy levels than to promote them across the large gap, the electrons remain paired. Consequently, low spin complexes have fewer unpaired electrons, which significantly impacts their magnetic properties, typically making them diamagnetic or weakly paramagnetic.
Key facts
| Field | Inorganic Chemistry |
|---|---|
| Cause | Strong-field ligands |
| Magnetic property | Usually diamagnetic or weakly paramagnetic |
The hexacyanoferrate(II) ion, [Fe(CN)6] 4-, is a classic low spin complex because the strong cyanide ligands force the iron's six d-electrons to pair up.
Frequently asked questions
How do you know if a complex will be low spin or high spin?
It depends on the strength of the ligands according to the spectrochemical series; strong-field ligands cause low spin complexes, while weak-field ligands cause high spin.