`[Fe(NO_2)_3Cl_3] and [Fe(O-NO_3Cl_3]` are

Options

A. linkage isomers
B. geometrical isomers
C. optical isomers
D. hydrate isomers

Answer

To determine the type of isomers for the complexes \([Fe(NO_2)_3Cl_3]\) and \([Fe(ONO)_3Cl_3]\), we will analyze the compounds step by step.

### Step 1: Identify the Ligands
- The first complex \([Fe(NO_2)_3Cl_3]\) contains the nitro ligand (\(NO_2^-\)) and chloride ions (\(Cl^-\)).
- The second complex \([Fe(ONO)_3Cl_3]\) contains the nitrito ligand (\(ONO^-\)) and chloride ions (\(Cl^-\)).

**Hint:** Look for ligands that can coordinate to the metal ion in different ways.

### Step 2: Determine the Type of Ligands
- The \(NO_2^-\) ligand can coordinate through the nitrogen atom (as nitro, \(NO_2^-\)) or through the oxygen atom (as nitrito, \(ONO^-\)).
- This means that \(NO_2^-\) is an ambidentate ligand, which can lead to linkage isomerism.

**Hint:** Ambidentate ligands can create different structural arrangements based on which atom they coordinate through.

### Step 3: Analyze Linkage Isomerism
- Since \(NO_2^-\) can bind through either nitrogen or oxygen, we can have two different structural isomers:
1. When \(NO_2^-\) binds through nitrogen, we have \([Fe(NO_2)_3Cl_3]\).
2. When \(NO_2^-\) binds through oxygen, we can represent it as \([Fe(ONO)_3Cl_3]\).

**Hint:** Linkage isomers arise when a ligand can attach to the metal in more than one way.

### Step 4: Check for Other Types of Isomerism
- **Geometrical Isomerism:** This occurs when ligands can be arranged differently in space. However, in this case, the arrangement does not lead to different geometrical isomers since the coordination number remains the same.
- **Optical Isomerism:** Optical isomers are non-superimposable mirror images. For these complexes, they do not have a plane of symmetry or a center of symmetry, but they are not chiral due to the presence of identical ligands.
- **Hydrate Isomerism:** This involves the presence of different numbers of water molecules in the coordination sphere, which is not applicable here as there are no water molecules.

**Hint:** Consider the arrangement of ligands and their symmetry to determine if geometrical or optical isomers are possible.

### Conclusion
From the analysis, we conclude that the complexes \([Fe(NO_2)_3Cl_3]\) and \([Fe(ONO)_3Cl_3]\) exhibit **linkage isomerism** due to the ability of the \(NO_2^-\) ligand to coordinate through either nitrogen or oxygen.

**Final Answer:** The complexes \([Fe(NO_2)_3Cl_3]\) and \([Fe(ONO)_3Cl_3]\) are linkage isomers.