The complex ion which has no.'d' electrons in the central metal atom is :

Options

A. `[MnO_(4)]^(-)`
B. `[Co(NH_(3))_(6)]^(3+)`
C. `[Fe(CN)_(6)]^(3-)`
D. `[Cr(H_(2)O)_(6)]^(3+)`

Answer

A

Explanation

In `MnO_(4)^(-)`, the O.S of Mn is +7 i.e., `Mn^(7+)`.

i.e. `3d^(0) 4s^(0)`
In other species, we have
Co in `[Co(NH_(3))_(6)]^(3+)" is " Co^(3+) i.e. 3d^(6)`
Fe in `[Fe(CN)_(6)]^(3-) " is " Fe^(3+) i.e. 3d^(5)`
Cr in `[Cr(H_(2)0)_(6)]^(3+)" is " Cr^(3+) i.e. 3d^(3)`
All of these have certain number of d-electrons.