Question

From the stability constants (hypothetical value) given below, predict the strongest ligand.

• A. $C{u}^{2+}+4N{H}_3\to {\left[Cu{\left(N{H}_3\right)}_4\right]}^{2+},K=4.5\times {10}^{11}$
• B. $C{u}^{2+}+4C{N}^{-}\to {\left[Cu{\left(CN\right)}_4\right]}^{2-},K=2.0\times {10}^{27}$
• C. $C{u}^{2+}+2en\to {\left[Cu{\left(en\right)}_2\right]}^{2+},K=3.0\times {10}^{15}$
• D. $C{u}^{2+}+4H_{2}O\to {\left[Cu{\left(H_{2}O\right)}_4\right]}^{2+},K=9.5\times {10}^8$

Answer 1

The correct option is B $C{u}^{2+}+4C{N}^{-}\to {\left[Cu{\left(CN\right)}_4\right]}^{2-},K=2.0\times {10}^{27}$

Higher the value of the stability constant, the more stable the complex indicating a stronger bond with the ligands.