( 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 .