question_answer

    Which one of the following complexes is an outer orbital complex?

A)  \[{{[Fe{{(CN)}_{6}}]}^{4-}}\]     

B)  \[{{[Mn{{(CN)}_{6}}]}^{4-}}\]

C)  \[{{[Co{{(N{{H}_{3}})}_{6}}]}^{3+}}\]     

D)  \[{{[Ni{{(N{{H}_{3}})}_{6}}]}^{2+}}\] (Atomic numbers\[Mn=25,\text{ }Fe=26,\text{ }Co=27,\] \[Ni=28\])

Correct Answer: D

Solution :

                (a)                 (b) (c)   (d)   In this case also\[N{{H}_{3}}\]is a strong ligand but electrons remain unpaired since only one orbital is left vacant in\[3d\]. Thus