Question

Classify the following ligands into monodentate, polydentate and ambidentate. i) NH₃ ii) CN⁻ iii) F⁻ iv) NCS⁻ v) NO₂⁻ vi) ethylene diammine vii) triaminotriethhhylamine

Answer 1

Unidentate ligands: Ligands with only one donor atom, e.g. NH3, Cl-, F- etc.

Bidentate ligands: Ligands with two donor atoms, e.g. ethylenediamine, C2O42-(oxalate ion) etc.

Tridentate ligands: Ligands which have three donor atoms per ligand, e.g. (dien) diethyl triamine.

Hexadentate ligands: Ligands which have six donor atoms per ligand, e.g. EDTA.

Chelating Ligands: Multidentate ligand simultaneously co-ordinating to a metal ion through more than one site is called chelating ligand. These ligands produce a ring like structure called chelate. Chelation increases the stability of complex. This effect is called chelation effect.