Which of the following is not an inner orbital complex ?

Options

A. `[Mn(CN)_(6)]^(3+)`
B. `[Fe(CN)_(6)]^(3-)`
C. `[Co(H_(2)O)_(6)]^(2+)`
D. `[Co(C_(2)O_(4))_(3)]^(3-)`

Answer

C

Explanation

In the formation of an inner orbital complex, the inner d orbital (3d) is used in hybridization. `[Mn(CN)_(6)]^(3-)[Fe(CN)_(6)]^(3-)` and `[Co(C_(2)O_(4))_(3)]^(3-)` are inner orbital complexes involving `d^(2) sp^(3)` hybrization. The first two complexes are paramagnetic corresponding to one unpaired electron while the third one is diamagnetic. Such complexes are unsually formed with strong field ligands `[Co(H_(2)O)_(6)]^(2+)` is an outer orbital complex involving `sp^(3) d^(2)` hybridization. Note that `H_(2)O` is a weak field ligand.