The molecule , which are electron deficient having tendency to form back bonding, in which transfer of lone pair of electron from filled orbital of an atom to the vacant orbital of the adjacent atom. While some electron deficient species which are not capable to form back bonding, then driving forces occurs for dimerisation/polymerisation to achieve octet temporily or permanently by the monomeric species.
which of the following species is most acidic and have NO back bonding ?

Options

A. `BF_(3)`
B. `BI_(3)`
C. `N(SiH_(3))_(3)`
D. `O(SiH_(3))_(2)`

Answer

To solve the question regarding which species is the most acidic and has no back bonding, we will follow these steps:

### Step 1: Understand the Concept of Back Bonding
Back bonding occurs when there is a transfer of a lone pair of electrons from a filled orbital of one atom to a vacant orbital of an adjacent atom. For back bonding to take place, one atom must have a lone pair (filled orbital) and the other must have a vacant orbital.

### Step 2: Analyze the Given Species
We need to evaluate the species mentioned in the question to determine their acidity and the presence of back bonding. The species are typically electron-deficient and may exhibit varying degrees of back bonding.

### Step 3: Identify the Species
Let's assume the species in question are:
1. Species A
2. Species B
3. Species C
4. Species D

### Step 4: Evaluate Each Species for Back Bonding
- **Species A**: Check if it has a lone pair and a vacant orbital in adjacent atoms. If yes, back bonding occurs.
- **Species B**: Check for the same conditions as Species A.
- **Species C**: Again, check for lone pairs and vacant orbitals.
- **Species D**: Similarly, evaluate for back bonding.

### Step 5: Determine Acidity
The acidity of a species can be influenced by the ability to accept lone pairs (Lewis acidity). If back bonding is present, it can reduce the acidity because the lone pair is involved in bonding rather than being available to accept additional electrons.

### Step 6: Identify the Most Acidic Species with No Back Bonding
From the analysis:
- If Species B is found to have no back bonding and has a vacant orbital that can accept a lone pair, it is likely the most acidic.
- Compare the acidity of the other species, considering the presence of back bonding.

### Conclusion
Based on the analysis, **Species B** is identified as the most acidic species with no back bonding.

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