QJEEM06Ch9099: JEE Main 2006 Chemistry - Class 12 JEEM06Ch9099 Solution: The IUPAC name for the complex [Co(NO 2 )(NH 3 ) 5 ]Cl 2 is

The IUPAC name for the complex $[\text{Co(NO}_2)(\text{NH}_3)_5]\text{Cl}_2$ is: Pentaammine(nitrito- $\text{N,O}$ )cobalt(III) chloride

Here's how to arrive at the name:

The complex is a cobalt complex, and cobalt has a +3 charge in this compound (since it has one negatively charged NO $_2$ ligand and one negatively charged Cl ion, for a total of -2, to balance the +3 charge on cobalt).

The ligands are NH $_3$ (ammonia) and NO $_2$ (nitrito).

Ammonia is a neutral ligand, so its name is just "ammine" and it is designated by the prefix "penta" because there are five of them.

Nitrito is a negatively charged ligand, so its name is "nitrito- $\text{N,O}$ " (the "- $\text{N,O}$ " indicates that the NO $_2$ ligand is bound through both the nitrogen and oxygen atoms).

Finally, the compound has a chloride ion, so its name is "chloride" and it is designated by the prefix "di" because there are two of them.

Putting it all together, we get the name "pentaammine(nitrito- $\text{N,O}$ )cobalt(III) chloride".