The polarity of (i) `(CH_3)_(2) P(CF_3)_(3)` and (ii) `(CH_3)_(3) P(CF_3)_(2)` respectively are?

Options

A. (i) Non Polar(ii) Polar
B. (i) Polar (ii) Non Polar
C. (i) Non Polar (ii) Non Polar
D. (i) Polar (ii) Polar

Answer

To determine the polarity of the compounds (i) `(CH_3)_(2) P(CF_3)_(3)` and (ii) `(CH_3)_(3) P(CF_3)_(2)`, we need to analyze their structures and the arrangement of their substituents around the central phosphorus atom.

### Step-by-Step Solution:

1. **Identify the Central Atom and Hybridization:**
- The central atom in both compounds is phosphorus (P).
- Phosphorus has the electronic configuration of 3s² 3p³. It can undergo hybridization to form sp³ hybrid orbitals, which allows it to form five bonds (triagonal bipyramidal geometry).

2. **Draw the Structures:**
- For `(CH_3)_(2) P(CF_3)_(3)`:
- Phosphorus is bonded to two methyl groups `(CH_3)` and three trifluoromethyl groups `(CF_3)`.
- The more electronegative `CF_3` groups will occupy the axial positions due to their higher electronegativity compared to `CH_3`.
- The structure will have two `CH_3` groups in equatorial positions and three `CF_3` groups in axial positions.

- For `(CH_3)_(3) P(CF_3)_(2)`:
- Phosphorus is bonded to three methyl groups `(CH_3)` and two trifluoromethyl groups `(CF_3)`.
- Again, the `CF_3` groups will occupy the axial positions, while the `CH_3` groups will occupy the equatorial positions.

3. **Analyze the Polarity:**
- **For `(CH_3)_(2) P(CF_3)_(3)`**:
- The `CF_3` groups are more electronegative and will pull electron density towards themselves, creating dipole moments.
- The dipole moments from the two `CF_3` groups in axial positions will cancel each other out, but the `CF_3` in the equatorial position will create a net dipole moment.
- Therefore, this molecule is **polar**.

- **For `(CH_3)_(3) P(CF_3)_(2)`**:
- The two `CF_3` groups in axial positions will have dipole moments that are equal in magnitude but opposite in direction, thus they will cancel each other out.
- The three `CH_3` groups will not contribute to any significant dipole moment.
- Therefore, this molecule is **non-polar**.

4. **Conclusion:**
- The polarity of `(CH_3)_(2) P(CF_3)_(3)` is **polar**.
- The polarity of `(CH_3)_(3) P(CF_3)_(2)` is **non-polar**.

### Final Answer:
- (i) Polar
- (ii) Non-polar