Question

Define each of the following.

1. weak-field ligand
2. strong-field ligand
3. low-spin complex
4. high-spin complex

Short answer

The definition of the above are given below.

Step-by-step solution

Step:1

Ligands are the lewis base- they contain at least one pair of electrons to donate to a metal atom/ion.

1. Weak –field ligand : Ligands which cause lower splitting of d-orbitals. They do not favour the pairing of electrons as there pairing energy is high. E.g. Cl, Br
2. Strong-field ligand: Ligands which cause higher splitting of d-orditals and they favour the pairing of electrons as there pairing energy is low.

Step:2

1. Low-spin complexis a complex in which there is maximum pairing of electrons in the orbitals of the metal atom. They are expected to occur with ligands that bond relatively strongly such as CN, NO, CO etc.
2. High-spin complexis a complex in which there is minimum pairing of electrons in the orbitals of the metal atom. They are expected to occur with weakly bonding ligands such as Cl, Br, H₂O etc.