The correct name for the complex ion `[CoCl(ONO)(en)_(2)]^(+)` is:

Options

A. chlorobis(ethylenediamine)nitrito-O-cobaltate (III) ion
B. chlorodiethyldiaminenitrito-O-cobalt (III) ion
C. chloronitrito-O-diethyldiamine cobaltate (III) ion
D. chlorobis(ethylenediamine) nitrito-O-cobalt (III) ion

Explanation

To name the complex ion \([CoCl(ONO)(en)_2]^+\), we will follow the systematic rules for naming coordination compounds. Here’s a step-by-step breakdown of the naming process:

### Step 1: Identify the Ligands
- The complex contains three types of ligands:
1. **Cl** (Chloride)
2. **ONO** (Nitrito, specifically nitrito-O)
3. **en** (Ethylene diamine)

### Step 2: Determine the Names of the Ligands
- **Chloride** is named as **chloro**.
- **Nitrito** (from ONO) is named as **nitrito**. Since it is bonded through the oxygen atom, we specify it as nitrito-O.
- **Ethylene diamine** is a bidentate ligand and is named as **ethylene diamine**. Since there are two ethylene diamine ligands, we use the prefix **bis**.

### Step 3: Arrange the Ligands Alphabetically
- When naming the ligands, we arrange them in alphabetical order, ignoring any prefixes (like bis).
- The order will be:
1. **chloro**
2. **nitrito**
3. **bis ethylene diamine**

### Step 4: Name the Central Metal Ion
- The central metal ion is cobalt (Co). Since the complex is positively charged, we simply use the name **cobalt** without any modification.

### Step 5: Combine the Names
- Combine the names of the ligands and the metal ion in the order determined:
- Start with the ligands: **bis ethylene diamine**, **chloro**, and **nitrito**.
- Follow with the name of the metal: **cobalt**.

### Step 6: Indicate the Oxidation State of the Metal
- The oxidation state of cobalt in this complex can be determined by considering the charges of the ligands:
- Chloride (Cl) has a charge of -1.
- Nitrito (ONO) has a charge of -1.
- Ethylene diamine (en) is neutral.

Therefore, the total charge contributed by the ligands is -2. Since the overall charge of the complex is +1, cobalt must be in the +3 oxidation state.

### Final Name of the Complex
Putting it all together, the complete name of the complex ion \([CoCl(ONO)(en)_2]^+\) is:
**bis(ethylene diamine) chloro nitrito cobalt(III)**.