The total possible co-ordination isomers for the following compounds respectively are
(i) `[Co(en)_(3)][Cr(C_(2)O_(4))_(3)]`
(ii) `[Cu(NH_(3))_(4)][CuCl_(4)]`
(iii) `[Ni(en)_(3)][Co(NO_(2))_(6)]`

Options

A. 4,4,4
B. 2,2,2
C. 2,2,4
D. 4,2,3

Answer

To determine the total possible coordination isomers for the given compounds, we will analyze each compound step by step.

### Step 1: Analyze the first compound `[Co(en)_(3)][Cr(C_(2)O_(4))_(3)]`
- **Ligands**: The cationic complex is `[Co(en)_(3)]`, where `en` (ethylenediamine) is a bidentate ligand. The anionic complex is `[Cr(C_(2)O_(4))_(3)]`, where `C_(2)O_(4)` (oxalate) is also a bidentate ligand.
- **Possible Isomers**: Since both ligands are bidentate, they can be exchanged between the cationic and anionic complexes. The charge must be conserved during this exchange.
- **Count of Isomers**:
- The possible exchanges are:
1. `[Co(en)_(3)][Cr(C_(2)O_(4))_(3)]`
2. `[Co(en)_(2)(C_(2)O_(4))][Cr(en)(C_(2)O_(4))_(2)]`
3. `[Co(en)(C_(2)O_(4))_(2)][Cr(en)_(2)(C_(2)O_(4))]`
4. `[Co(C_(2)O_(4))_(3)][Cr(en)_(3)]`
- **Total Isomers**: There are **4 coordination isomers** for this compound.

### Step 2: Analyze the second compound `[Cu(NH_(3))_(4)][CuCl_(4)]`
- **Ligands**: The cationic complex is `[Cu(NH_(3))_(4)]`, and the anionic complex is `[CuCl_(4)]`.
- **Possible Isomers**: Here, both complexes contain copper as the central metal ion. The ligands can be exchanged, but we must ensure charge conservation.
- **Count of Isomers**:
- Possible exchanges:
1. `[Cu(NH_(3))_(4)][CuCl_(4)]`
2. `[Cu(NH_(3))_(3)Cl][CuCl_(3)(NH_(3))]`
- **Total Isomers**: There are **2 coordination isomers** for this compound.

### Step 3: Analyze the third compound `[Ni(en)_(3)][Co(NO_(2))_(6)]`
- **Ligands**: The cationic complex is `[Ni(en)_(3)]`, where `en` is a bidentate ligand. The anionic complex is `[Co(NO_(2))_(6)]`, where `NO_(2)` is a monodentate ligand.
- **Possible Isomers**: In this case, since `en` is bidentate and `NO_(2)` is monodentate, when exchanging ligands, we must exchange two `NO_(2)` ligands for each `en`.
- **Count of Isomers**:
- Possible exchanges:
1. `[Ni(en)_(3)][Co(NO_(2))_(6)]`
2. `[Ni(en)_(2)(NO_(2))][Co(en)(NO_(2))_(5)]`
3. `[Ni(en)(NO_(2))_(2)][Co(en)_(2)(NO_(2))_(4)]`
- **Total Isomers**: There are **3 coordination isomers** for this compound.

### Final Summary of Coordination Isomers
1. For `[Co(en)_(3)][Cr(C_(2)O_(4))_(3)]`: **4 isomers**
2. For `[Cu(NH_(3))_(4)][CuCl_(4)]`: **2 isomers**
3. For `[Ni(en)_(3)][Co(NO_(2))_(6)]`: **3 isomers**