Question

Which one of the following metal complexes is most stable ?

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• A. $\left[Co\right(en{)}_2\left(N{H}_3{)}_2\right]C{l}_2$
• B. $\left[Co\right(en{)}_3]C{l}_2$
• C. $\left[Co\right(N{H}_3{)}_6]C{l}_2$
• D. $\left[Co\right(en\left)\right(N{H}_3{)}_4]C{l}_2$

Answer 1

The correct option is B $\left[Co\right(en{)}_3]C{l}_2$

Cyclic complexes, called chelates, are generally more stable than open chain complexes. Chelates having more number of cyclic rings are more stable than those having less number of cyclic rings.
$\therefore$ Of the given complexes $\left[Co\right(en{)}_3]C{l}_2$ is most stable.