Question

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 $ )

Answer 1

Answer: (D)

(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