( iv) Ambidentate ligands These are the monodentate ligands which can ligate through two different sites, e. g., NO-2, SCN-, etc.
( v) Chelating ligands Di or polydentate ligands cause cyclisation around the metal atom which are known as chelate IS, Such ligands USes two or more donor atoms to bind a single metal ion and are known as chelating ligands.
More the number of chelate rings, more is the stability of complex.
The stabilisation of coordination compounds due to chelation is known as chelate effect.
π – acid ligands are those ligands which can form π – bond and n-bond by accepting an appreciable amount of 1t electron density from metal atom to empty π or π – orbitals.
4. Coordination Number
It is defined as the number of coordinate bonds formed by central metal atom, with the ligands.
e. g., in [ PtCI6 ] 2-, Pt has coordination number 6.
In case of monodentate ligands, Coordination number = number of ligands
In polydentate ligands. Coordination number = number of ligands * denticity
5. Coordination Sphere
The central ion and the ligands attached to it are enclosed in square bracket which is known as coordination sphere. The ionisable group written outside the bracket is known as counter ions.