Question

The primary and secondary valency of a central metal ion in $\left[Co\right(N{H}_3{)}_{4}C{O}_3]$$Cl$ complex is _________ and _________ respectively.

• A. $2,6$
• B. $4,6$
• C. $4,5$
• D. $3,6$

Answer 1

The correct option is D $3,6$

The primary and secondary valency of cobalt ion is 3 and 6 respectively.

The charge on cobalt ion is $+3$ which balances $-2$ charge on carbonate ion and $-1$ charge on chloride ion. Hence, the primary valency of cobalt ion is 3.

Cobalt ion is surrounded by four monodentate and one bidentate ligand (4 ammonia and on carbonate) in the coordination sphere. Hence, its coordination number (secondary valency) is 6.