Compounds of the type R-Mg-X are known as..............

Explanation

**Step-by-Step Solution:**

1. **Understanding the Structure**: The compound of the type R-Mg-X consists of three components: R, Mg, and X. Here, R represents an alkyl or aryl group, Mg stands for magnesium, and X represents a halogen atom (such as Cl, Br, or I).

2. **Identifying the Compound Type**: Compounds that have this structure are classified based on their functional groups. The presence of magnesium and a halogen indicates that this compound is a type of organometallic compound.

3. **Naming the Compound**: The specific name for compounds of the type R-Mg-X is "Grignard reagents." This name is derived from the chemist François Auguste Victor Grignard, who discovered these compounds.

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