question_answer

Formation constant \[{{K}_{f}}\]for the two complex ions are: \[{{[Ni{{(en)}_{3}}]}^{2+}};{{K}_{f}}=1.1\times {{10}^{18}}\,\,and\]\[{{[Ni{{(N{{H}_{3}})}_{6}}]}^{2+}};\,\,{{K}_{f}}=5.3\,\times {{10}^{8}}\] Explain the relative stability of these complexes.

Answer:

                In the first complex ; 'en' is didentate ligand and has much larger formation constant than 'ammine' present in the second complex which is only a unidentate ligand. Moreover, 'en' is also involved in the formation of chelate (chelation effect) and the complex has extra stability.