A complex anion is formed by Osmium ( in some oxidation state ) with ligands ( in proper number so that coordination number of osmium becomes six ). Which of the following can be its correct IUPAC name ?

Options

A. pentachloridonitridoosmium(VI)
B. pentachloridonitridoosmate(VI)
C. azidopentachloridoosmate(VI)
D. None of these

Answer

To solve the problem of determining the correct IUPAC name for a complex anion formed by osmium with a coordination number of six, we can follow these steps:

### Step 1: Identify the oxidation state of osmium
- In the complex, osmium can have various oxidation states. For this problem, we will assume it is in the +6 oxidation state, which is common for osmium in coordination compounds.

### Step 2: Determine the ligands and their charges
- The problem states that the coordination number of osmium is six. This means that the total number of ligands must equal six.
- We can choose ligands such as chloride ions (Cl⁻) and azide ions (N₃⁻) to achieve this. For example, we can have five chloride ions and one azide ion.

### Step 3: Calculate the overall charge of the complex
- If we have five chloride ions (each with a -1 charge) and one azide ion (with a -1 charge), the total charge contributed by the ligands is:
- Charge from Cl⁻: 5 × (-1) = -5
- Charge from N₃⁻: -1
- Total charge from ligands = -5 + (-1) = -6
- The oxidation state of osmium is +6, so the overall charge of the complex is:
- Charge of osmium + Total charge from ligands = +6 - 6 = 0
- Since the overall charge is zero, this indicates that the compound is neutral.

### Step 4: Write the IUPAC name for the complex
- The IUPAC naming convention requires us to name the ligands first, followed by the metal and its oxidation state in Roman numerals.
- The ligands are named in alphabetical order regardless of their charge. Here, we have:
- Five chloride ligands: "pentachlorido"
- One azide ligand: "nitrido"
- The name of the metal is "osmium" and its oxidation state is +6, which is denoted as "osmium(VI)".
- Therefore, the complete IUPAC name for the complex is "pentachlorido nitrido osmium(VI)".

### Final Answer
The correct IUPAC name for the complex anion formed by osmium with a coordination number of six is **pentachlorido nitrido osmium(VI)**.

---