Question

Consider the following complex,

$\left[Co\right(N{H}_3{)}_{5}C{O}_3]Cl{O}_4$

The coordination number, oxidation number, number of $d-$electrons and number of unpaired $d-$electrons on the metal are respectively:

• A. 6, 3, 6. 0
• B. 7, 2, 7, 1
• C. 7, 1, 6, 4
• D. 6, 2, 7, 3

Answer 1

The correct option is A 6, 3, 6. 0

From the complex we get,

Total negative charge $C{O}_3^{2-}+Cl{O}_4^{1-}=-3$

Hence, oxidation number of $Co$ is $+3$

Coordination number is $6$ as it is surrounded by $5N{H}_3$ molecules and $1$ $C{O}_3^{2-}$ molecules.

Hence, there are 6 $d$ electrons and all are paired. (Since the NH3 is strong ligand).