Which of the following complex ion is not expected to absorb visible light?

Options

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

Answer

A

Explanation

Due to the presence of strong field ligand `CN^(-)` , in the `N^(2+)` ion ( `d^(8)` configuration ) all the four d-orbitals get paired up. In the absence of an unpaired electron, d-d transition is not possible. Therefore, no radiations are absorbed from the visible region of light.