Choose incorrect stability order:

Options

A. `[Cu(NH_(3))_(4)]^(2+) lt [Cu(en)_(2)]^(2+) lt [Cu("trien")]^(2+)`
B. `[Fe(H_(2)O)_(6)]^(3+) lt [Fe(NO_(2))_(6)]^(3-) lt [Fe(NH_(3))_(6)]^(3+)`
C. `[Co(H_(2)O)_(6)]^(3+) lt [Rh(H_(2)O)_(6)]^(3+) lt [Ir(H_(2)O)_(6)]^(3+)`
D. `[Cr(NH_(3))_(6)]^(1+) lt [Cr(NH_(3))_(6)]^(2+) lt [Cr(NH_(3))_(6)]^(3+)`

Explanation

To solve the question of choosing the incorrect stability order, we will follow a systematic approach based on the strength of ligands and the oxidation states of the central metal atom. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Stability Order
The stability of coordination compounds is influenced by:
- The nature of the central metal atom (its oxidation state).
- The strength of the ligands attached to the metal.

### Step 2: Review the Spectrochemical Series
The spectrochemical series ranks ligands based on their field strength:
1. Weak field ligands: Iodide (I⁻), Bromide (Br⁻), Chloride (Cl⁻)
2. Moderate field ligands: Water (H₂O), Hydroxide (OH⁻), Nitrite (NO₂⁻)
3. Strong field ligands: Ammonia (NH₃), Ethylenediamine (en), Cyanide (CN⁻)

### Step 3: Analyze the Given Options
We need to evaluate the stability orders provided in the options. The question states that we need to find the incorrect order.

#### Option Analysis:
1. **Option 1**: Amine (NH₃) < Ethylenediamine (en) < Tri-N (trien)
- This order is correct as ethylenediamine is a stronger ligand than ammonia.

2. **Option 2**: Aqua (H₂O) < Nitrite (NO₂⁻) < Amine (NH₃)
- This order is incorrect. According to the spectrochemical series, nitrite (NO₂⁻) is a stronger ligand than ammonia (NH₃). Thus, the correct order should be: Aqua < Nitrite < Amine.

3. **Option 3**: Cobalt (Co) < Rhodium (Rh) < Iridium (Ir)
- This order is correct as stability increases down the group due to the involvement of inner d-orbitals.

4. **Option 4**: Chromium oxidation states (Cr²⁺, Cr³⁺, Cr⁶⁺)
- This order is also correct as the stability of chromium complexes generally increases with higher oxidation states.

### Step 4: Conclusion
From the analysis, the incorrect stability order is found in **Option 2** where it incorrectly states that NO₂⁻ is less stable than NH₃.

### Final Answer
The incorrect stability order is: Aqua < Nitrite < Amine (Option 2).

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