Question

Differentiate between weak field and strong field ligands. How does the strength of the ligand influence the spin of the complex?

Answer 1

Weak field ligands cause a small splitting of d-orbitals, which does not result in electron pair- ing. As a result, the complex will have high-spin configuration with more unpaired electrons. Examples of weak field ligands include halides and water.
Strong field ligands cause a large splitting of d-orbitals, which results in electron pairing and low-spin configuration with fewer unpaired electrons. Examples of strong field ligands include CO and CN−.