SME
Inorganic Chemistry · Problem type
The spectrochemical series
Use this for “Which gives the larger Δₒ with Co³⁺: fluoride, ammonia or cyanide? Which complex is more likely low spin?”
Put in order
Order from the weakest-field ligand to the strongest.
1
?
2
?
3
?
4
?
5
?
6
?
Assumptions
•
The order holds for nearly every metal ion; it is read from the spectra of their complexes.
•
Halides give the field away with their filled p orbitals (π donors), which shrinks Δₒ.
•
CN⁻ takes metal d electrons back into its empty π∗ orbitals (a π acceptor), which widens Δₒ the most.
•
A strong-field ligand gives a big Δₒ, so its complexes are more often low spin.
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