Which of the following is expected to be a paramagnetic complex?

Options

A. `[Ni(H_(2)O)_(6)]^(2+)`
B. `[Ni(CO)_(4)]`
C. `[Zn(NH_(3))_(4)]^(2+)`
D. `[Co(NH_(3))_(6)]^(3+)`

Answer

A

Explanation

In `[Ni(H_(2)O)_(6)]^(2+)` configuration of `Ni^(2+) is [Ar^(18)] 3d^(8)` Hybridisation is `sp^(3)d^(2)` . There are two unpaired electrons and hence complex is paramagnetic.
For structure of `Ni(CO)_(4)` see Q . 44 above . It is diamagnetic.
In `[Zn(NH_(3))_(4)^(2+), Zn^(2+)` has cnfiguration of `[Ar^(18)]3d^(10)`. It is diamagnetic .
For structure of `[Co(NH_(3))_(6)]^(3+)`. See Q. 26 . It is diamagntic