Which of the following will give a pair of enontiomorphs ?
`en = NH_(2)CH_(2)CH_(2)NH_(2)`

Options

A. `[Cr(NH_(3))_(6)][Co(CN)_(6)]`
B. `[Co(en)_(2)Cl_(2)]Cl`
C. `[Pt(NH_(3))_(4)][PtCl_(6)]`
D. `[Co(NH_(3))_(4)Cl_(2)]NO_(2)`

Explanation

To determine which of the given coordination compounds will give a pair of enantiomers (enantiomorphs), we need to analyze their structures and geometries. Here’s a step-by-step breakdown of the solution:

### Step 1: Understanding Enantiomers
Enantiomers are a type of stereoisomer that are non-superimposable mirror images of each other. They typically arise in chiral molecules, which lack an internal plane of symmetry.

**Hint:** Look for chiral centers or geometries that can lead to non-superimposable mirror images.

### Step 2: Analyze the Given Compound
The compound given is `en = NH2CH2CH2NH2`, which is ethylenediamine (en). It is a bidentate ligand, meaning it can form two bonds with a metal ion.

**Hint:** Identify the ligands and their bonding capabilities.

### Step 3: Identify the Coordination Complex
Let’s consider a coordination complex with cobalt (Co) as the central metal atom, where ethylenediamine (en) and chloride ions (Cl) are the ligands. The possible coordination compounds can be represented as:
1. [Co(en)2Cl2]
2. [Co(en)Cl3]

**Hint:** Write down the possible coordination compounds based on the ligands provided.

### Step 4: Determine the Geometry
For the complex [Co(en)2Cl2], the geometry is octahedral. In an octahedral complex, the arrangement of ligands can lead to different isomers.

**Hint:** Visualize the 3D arrangement of ligands around the central metal ion.

### Step 5: Analyze Isomers
1. **Trans Isomer**: In the trans isomer of [Co(en)2Cl2], the two chloride ions are opposite each other, leading to a symmetrical structure. This structure has a plane of symmetry and will not exhibit optical activity (no enantiomers).

2. **Cis Isomer**: In the cis isomer, the two chloride ions are adjacent. This arrangement can lead to a chiral structure because it lacks a plane of symmetry. Drawing the mirror image of this cis isomer will show that it cannot be superimposed on the original structure, indicating that they are enantiomers.

**Hint:** Draw both the cis and trans isomers to visualize their symmetry properties.

### Step 6: Conclusion
The only coordination compound from the options that can give rise to a pair of enantiomers is the cis isomer of [Co(en)2Cl2]. Therefore, the answer to the question is option B.

**Final Answer:** Option B will give a pair of enantiomorphs.