Question

Select correct statements(s) about $[CoC{l}_6{]}^{4-}$ complex.

• A. It is paramagnetic
• B. It is a low-spin complex
• C. Oxidation number of cobalt is -4
• D. The coordination number of cobalt is 6

Answer 1

Answer: (A), (D)

It is paramagnetic
The coordination number of cobalt is 6

In $[CoC{l}_6{]}^{4-}$, the central cobalt atom has the oxidation number of +2.
The outer electronic configuration is $3d^7$.
It is a high spin complex as the chloride ligand is weak field ligand.
it contains 3 unpaired electrons and is paramagnetic.
Since the cobalt is coordinated to 6 chlorine atoms, its coordination number is 6.
Thus, the options A and D are correct and the options B and C are incorrect.