Question

Consider the following statements in respect of $[CoC{l}_6{]}^{4-}$ complex ion-
I: It is paramagnetic
II: It is low-spin complex.
III: Oxidation number of cobalt is-4.
IV: The coordination number of cobalt is 6.
Select correct statements.

• A. All of the above.
• B. III and IV only.
• C. I and IV only.
• D. I and II only.

Answer 1

The correct option is C I and IV only.

$[CoC{l}_6{]}^{4-}$- Cobalt is in +2 oxidation state. It's configuration is $\left[Ar\right]3d^7$. Since the ligand is weak the complex will be high-spin.Complex is paramagnetic owning to the unpaired electrons.