The IUPAC name of the complex `[Co(NO_2)(NH_3)_5]Cl_2` is

Options

A. Pentamminenitrocobalt (III) chloride
B. Pentamminenitrosocobalt (III) chloride
C. Pentamminenitraetcobalt (III) chloride
D. None of these

Answer

To determine the IUPAC name of the complex \([Co(NO_2)(NH_3)_5]Cl_2\), we can follow these steps:

### Step 1: Identify the Components of the Complex
- The complex consists of a central metal ion, which is cobalt (Co).
- It has two types of ligands: nitrito (NO₂) and ammonia (NH₃).
- There are also two chloride ions (Cl⁻) as counter ions.

### Step 2: Determine the Oxidation State of the Metal
- Let the oxidation state of cobalt be \(x\).
- The nitrito ligand (NO₂) is a negatively charged ligand with a charge of -1.
- The ammonia ligand (NH₃) is a neutral ligand with a charge of 0.
- The two chloride ions contribute a total charge of -2.
- The overall charge of the complex is neutral, so we can set up the equation:
\[ x + (-1) + 0 + 0 + 0 + (-2) = 0 \]
Simplifying gives:
\[ x - 3 = 0 \implies x = +3 \]
- Therefore, cobalt is in the +3 oxidation state.

### Step 3: Name the Ligands
- The ligands are named in alphabetical order regardless of their prefixes.
- The ligand NH₃ is called "ammine."
- The ligand NO₂ is called "nitrito" when it is bonded through nitrogen (N) and "nitro" when it is bonded through oxygen (O). In this case, it is bonded through nitrogen, so we use "nitrito."

### Step 4: Combine the Names
- Since we have five ammonia ligands, we use the prefix "penta" for ammine.
- The name of the complex will be:
\[ \text{pentaammine nitrito cobalt(III)} \]

### Step 5: Add the Counter Ion
- The counter ion is chloride, which is named as "chloride."
- Since the complex is cationic, we add "chloride" at the end.

### Final IUPAC Name
Putting it all together, the IUPAC name of the complex \([Co(NO_2)(NH_3)_5]Cl_2\) is:
\[ \text{pentaammine nitrito cobalt(III) chloride} \]