Etherates are

Options

A. Ethers
B. Solution in ether
C. Complexes of ethers with Lewis acid
D. Complexes of ethers with Lewis base

Answer

### Step-by-Step Solution

1. **Definition of Etherates**: Etherates are defined as compounds that form complexes between ethers and Lewis acids.

2. **Understanding Ethers**: Ethers have the general formula ROR, where R represents an alkyl group. This means that ethers consist of two alkyl groups connected by an oxygen atom.

3. **Understanding Lewis Acids**: Lewis acids are defined as species that can accept electron pairs. They typically have vacant orbitals that allow them to accept electrons from other molecules.

4. **Example of Etherate**: A common example of an etherate is boron trifluoride diethyl etherate.

5. **Chemical Formulas**:
- Boron trifluoride is represented as BF3. In this compound, boron has a vacant orbital.
- Diethyl ether has the formula C2H5OC2H5. In this structure, the oxygen atom has lone pairs of electrons.

6. **Formation of Etherate**: The formation of the etherate occurs when the lone pairs of electrons on the oxygen atom of diethyl ether are donated to the boron atom in BF3. This results in the formation of the complex BF3·(C2H5)2O.

7. **Conclusion**: Therefore, etherates are complexes formed between ethers and Lewis acids, exemplified by boron trifluoride diethyl etherate.