Which of the following coordinate compounds would exhibit optical isomerism?

Options

A. Pentaamminenitrocobalt (III) iodide
B. Diamminedichloroplatinum (II)
C. Trans - dicyanobis (ethylenediamine) chromium (III) chloride
D. Tris - (ethylenediamine) cobolt (III) bromide

Answer

To determine which of the given coordinate compounds exhibit optical isomerism, we need to analyze each compound based on its symmetry properties. Optical isomerism occurs when a compound lacks a plane of symmetry or a center of symmetry, allowing it to exist in two non-superimposable mirror images (enantiomers).

### Step-by-Step Solution:

1. **Identify the Compounds:**
- Pentaammine nitro cobalt(III) iodide
- Diamine dichloroplatinate(II)
- Trans-dicyano-bis(ethylenediamine)chromium(III) chloride
- Tris(ethylenediamine)cobalt(III) bromide

2. **Analyze Each Compound for Symmetry:**
- **Pentaammine nitro cobalt(III) iodide:**
- This compound has a cobalt center coordinated to five ammonia ligands and one nitro group. The arrangement creates a geometry that has a plane of symmetry due to the identical ammonia ligands. Thus, it does not exhibit optical isomerism.

- **Diamine dichloroplatinate(II):**
- This compound has a platinum center with two ammonia ligands and two chloride ligands. The square planar geometry allows for a plane of symmetry, meaning it does not exhibit optical isomerism.

- **Trans-dicyano-bis(ethylenediamine)chromium(III) chloride:**
- In this compound, the chromium center is coordinated to two cyano groups and two ethylenediamine ligands in a trans configuration. The trans arrangement introduces a plane of symmetry, making it optically inactive.

- **Tris(ethylenediamine)cobalt(III) bromide:**
- This compound has a cobalt center coordinated to three ethylenediamine ligands and one bromide ion. The arrangement can lead to a chiral configuration where the ethylenediamine ligands can be arranged in such a way that there is no plane of symmetry, allowing for optical isomerism.

3. **Conclusion:**
- The only compound that exhibits optical isomerism is **Tris(ethylenediamine)cobalt(III) bromide**.

### Final Answer:
**Tris(ethylenediamine)cobalt(III) bromide** exhibits optical isomerism.