Question

What is meant by the chelate effect? Give an example

Answer 1

When a ligand attaches to the metal ion in a manner that forms a ring, then the metal- ligand association is found to be more stable. In other words, we can say that complexes containing chelate rings are more stable than complexes without rings. This is known as the chelate effect.
For example
$Ni^{2+}_{(aq)}+6NH_{3(aq)}\leftrightarrow[Ni(NH_3)_6]^{2+}_{(aq)}$
$logβ=7.99$
$Ni^{2+}_{(aq)}+3en_{(aq)}\leftrightarrow[Ni(en)_3]^{2+}_{(aq)}$
$logβ=18.1(more \space stable)$