Question

IUPAC name of $N{a}_3\left[Co\right(N{O}_2{)}_6]$ is _____________.

• A. sodium hexanitrocobaltate (III)
• B. sodium cobaltnitrate
• C. trisodium hexanitrocobalt
• D. hexanitrocobalt (III) trisodium complex

Answer 1

Answer: (A)

sodium hexanitrocobaltate (III)

First, we note that the name of the counter ion is sodium. Now we write the name of the complex ion. It contains cobalt (III), so it will be called as cobaltate(III). We can determine the oxidation number of cobalt by charge balance. Also, it contains 6 $N{O}_2^{-}$ groups so it will be hexanitro.
Combining, we get that the name of the negative ion is hexanitrocobaltate(III). So, the name of the compound becomes sodium hexanitro cobaltate(III).