IUPAC name of Na_3 [Co(ONO)_6 ] is:

MCQ

$\text{IUPAC}$ name of $\mathrm{Na}_3\left[\mathrm{Co}(\mathrm{ONO})_6\right]$ is:

A
Sodium cobaltinitrite
✓
Sodium hexanitritocobaltate $(\text{III})$
C
Sodium hexanitrocobalt $(\text{III})$
D
Sodium hexanitritocobaltate $(II)$

✓

Answer

Correct option: B.

Sodium hexanitritocobaltate $(\text{III})$

The above complex $\mathrm{Na}_3\left[\mathrm{Co}(\mathrm{ONO})_6\right]$ has two ions$:\ Na^+$ and a complex ion which is negatively charged $\left[\mathrm{Co}(\mathrm{ONO})_6\right]^{3-}$
According to the rules, name of the positive ion comes first $($i.e., sodium$),$ do not mention the number of sodium as it is not present in a square bracket.
After naming the positive ion, next will be the negative ion, Now in this example, the negative ion is a complex compound, which contain's 'metal' and 'ligand'.
While naming a complex, name of ligand comes first, also mention the number of ligand by using prefix $($di, tri, tetra. etc..$)$ and if a bidentate ligand is present then mention the atom which is attached to central metal $($i.e., hexanitrito $−O−)$ followed by name of metal with the ending 'ate' $($i.e., cobaltate, always use the word 'ate' if the complex is negatively charge$)$ and than oxidation number of metal.
To show the oxidation state, we use Roman numerals inside parenthesis.