Question

Which of the following complexes has the highest negative energy change ($\Delta G$)?

• A. $\left[Ni\right(N{H}_3{)}_2(H_{2}O{)}_4{]}^{2+}$
• B. $\left[Ni\right(N{H}_3{)}_4(H_{2}0{)}_2{]}^{2+}$
• C. $\left[Ni\right(en\left)\right(H_{2}O{)}_4{]}^{2+}$
• D. $\left[Ni\right(en{)}_2(H_{2}O{)}_2{]}^{2+}$

Answer 1

The correct option is D $\left[Ni\right(en{)}_2(H_{2}O{)}_2{]}^{2+}$

More the stability of the complex, more is the magnitude of the negative energy change. The stability of the complex is greatly enhanced by the presence of a chelating ligand. This is known as the chelate effect. Thus the complex, $\left[Ni\right(en{)}_2(H_{2}O{)}_2{]}^{2+}$ has the highest negative energy change.