Which of the following species is most basic and have NO back bonding ?

Options

A. `P(SiH_(3))_(3)`
B. `N(CH_(3))_(3)`
C. `N(SiH_(3))_(3)`
D. `BCl_(3)`

Answer

To determine which of the given species is the most basic and has no back bonding, we will analyze each option step by step.

### Step 1: Understand Basicity
Basicity refers to the ability of a species to donate a lone pair of electrons. A more basic species has a higher tendency to donate its lone pair.

### Step 2: Identify Back Bonding
Back bonding occurs when there is a partial double bond character due to the donation of electron density from a filled orbital of one atom to an empty orbital of another atom. This can reduce the availability of lone pairs for donation, thus decreasing basicity.

### Step 3: Analyze Each Option
1. **Option A: Phosphorus connected to Silicon Hydrides (SiH₄)**
- Phosphorus has a lone pair of electrons.
- Silicon has empty d-orbitals, which can accept electron density from phosphorus.
- This leads to back bonding, which decreases the basicity of phosphorus in this compound.

2. **Option B: Nitrogen connected to three Methyl groups (CH₃)**
- Nitrogen has a lone pair of electrons.
- Carbon does not have empty d-orbitals to accept electron density.
- The methyl groups are electron-donating (inductive effect), which increases the electron density on nitrogen.
- There is no back bonding because carbon lacks empty orbitals, making this species more basic.

3. **Option C: Nitrogen connected to Silicon Hydrides (SiH₄)**
- Similar to option A, nitrogen has a lone pair.
- Silicon can accept electron density due to its empty d-orbitals, leading to back bonding.
- This decreases the basicity of nitrogen in this compound.

4. **Option D: Boron connected to Chlorine (Cl) and Bromine (Br)**
- Boron has an empty p-orbital and is electron-deficient.
- Chlorine and bromine can donate electron density, but boron cannot effectively donate a lone pair due to its deficiency.
- There may be some back bonding due to the empty p-orbital of boron, but boron is not basic.

### Step 4: Conclusion
After analyzing all options, we find that:
- **Option B** (Nitrogen connected to three methyl groups) is the most basic and has no back bonding due to the absence of empty orbitals in carbon.

### Final Answer
**Option B is the most basic and has no back bonding.**

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