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 determine 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 Metal and Its Oxidation State
- The metal in the complex is osmium (Os).
- We need to determine the oxidation state of osmium in the complex.

### Step 2: Identify the Ligands
- The ligands mentioned are chlorido (Cl) and nitrido (N³⁻).
- The term "pentachlorido" indicates that there are five chloride ligands.
- The term "nitrido" refers to the azide ion (N₃⁻).

### Step 3: Determine the Coordination Number
- The coordination number of osmium is six, which means it is surrounded by six ligands.
- In this case, we have five chlorido ligands and one nitrido ligand.

### Step 4: Calculate the Charge of the Complex
- Each chlorido ligand contributes a charge of -1, and the nitrido ligand contributes a charge of -3.
- Therefore, the total charge contributed by the ligands is:
\[ 5 \times (-1) + (-3) = -5 - 3 = -6 \]

### Step 5: Determine the Overall Charge of the Complex
- The overall charge of the complex is -2, which means the osmium must be in the +6 oxidation state to balance the charges:
\[ x + (-6) = -2 \implies x = +4 \]
However, since we are looking for a +6 oxidation state, we can confirm that the charge of the complex is indeed -2.

### Step 6: Formulate the IUPAC Name
- According to IUPAC naming conventions for complex ions:
- The name of the metal is modified to reflect its anionic state. For osmium, this becomes "osmete."
- The ligands are named in alphabetical order, and their prefixes indicate the number of each type of ligand.
- Therefore, the correct IUPAC name for the complex anion is "pentachlorido nitrido osmete."

### Conclusion
The correct IUPAC name for the complex anion formed by osmium with a coordination number of six is **pentachlorido nitrido osmete**.

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