why are chelate complexes more stable?
Stability of chelate complexes is directly related to the Entropy factor.
Enthalpy change for the reactions with chelating and non chelating ligands are almost same.When a chelating ligand replaces a non chelating ligand in the complex the change in entropy is positive for the reaction.That is ∆S is positive. Thus ∆G BECOMES NEGATIVE favouring the formation of chelating complex.
For eg :
We can see in reaction 1) Three en molecule replaces 6 NH3 and thus increasing the entropy of the system and favouring the reaction.
2) In reaction 2 when en is attached to the central metal atom ,the change in entropy is more as compared to the change in entropy when NH3 is attached as ligand because increase in disorderedness or no. of molecule is greater in case 1.
Enthalpy change for the reactions with chelating and non chelating ligands are almost same.When a chelating ligand replaces a non chelating ligand in the complex the change in entropy is positive for the reaction.That is ∆S is positive. Thus ∆G BECOMES NEGATIVE favouring the formation of chelating complex.
For eg :
We can see in reaction 1) Three en molecule replaces 6 NH3 and thus increasing the entropy of the system and favouring the reaction.
2) In reaction 2 when en is attached to the central metal atom ,the change in entropy is more as compared to the change in entropy when NH3 is attached as ligand because increase in disorderedness or no. of molecule is greater in case 1.