Explain the following terms giving a suitable example in each case:

(i) Ambident ligand

(ii) Denticity of a ligand

(iii) Crystal field splitting in an octahedral field

(i) The word ‘ambi’ means both are doing two things at the same time. So from the name itself we can identify what ambident ligands are. They are ligands which can coordinate to central metal atom through two different atoms is called ambident ligand.

For example, the thiocyanate ion, SCN- can bind to the central metal at either the sulphur or the nitrogen. In isothiocyanates, the substituent is attached to nitrogen.

(ii) Denticity of a ligand is the number of donor atoms of the ligand when it is bound with the central atom in a coordination complex or the number of coordinating groups present in ligand. For example, ethane-1, 2-diamine is a bidentate ligand as it has two donor nitrogen atoms which can link to central metal atom.

(iii) Crystal field splitting is the splitting of five degenerate d-orbitals in two sets, one with three orbitals and another with two orbitals. The splitting of the degenerated d-orbitals is done into three orbitals of lower energy, t_2g set and two orbitals of higher energy e_g, set due to the presence of any ligands in a octahedral crystal field.

Crystal field splitting.