Which of the following complex compounds will exhibit highest magnetic behaviour ?
`(At.No. Ti = 22, Cr = 24, Co = 27, Zn = 30)`

Options

A. `[Zn (NH_(3))_(6)]^(2+)`
B. `[Ti(NH_(3))_(6)]^(3+)`
C. `[Cr(NH_(3))_(6)]^(3+)`
D. `[Co(NH_(3))_(6)]^(3+)`

Answer

C

Explanation

`Zn^(2+) ([Ar]3d^(10))` has zero unpaired electron. In the complex, they occupy both `t_(2g)` and `e_(g)` set of orbitals. `Ti^(3+) ([Ar]3d^(1))` has one unpaired electron. In the complex, the single 3d electron occupies one of the lower energy `t_(2g)` orbitals. `Cr^(3+) ([Ar]3d^(3))` has three unpaired electrons: In the complex, they occupy the lower energy set of `t_(2g)` orbitals `t_(2g)^(3)` `e_(g)^(0)` `Co^(3+) ([Ar]3d^(6))` can have a high spin or low or low spin configuration. Because `NH_(3)` is a relatively strong field ligands, all six electrons go into lower energy `t_(2g)` orbitals. The configuration is low-spin with zero unpaired electron `(t_(2)^(6)e_(g)^(0))` .