How do Grignard reagents behave like carbanions?

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periodic table with group numbers and the s, p, d, and f blocks — organometallic compound The periodic table of the elements, displaying the group numbers and the s, p, d, and f blocks. Elements in the shaded area are the metals of organometallic chemistry.

Grignard reagents, which are organic derivatives of magnesium with the general formula RMgX, behave like carbanions because they contain a carbon atom that acts as if it carries a negative charge.1

In this chemical context, the carbon atom bonded to the magnesium is highly nucleophilic and basic, mirroring the behavior of a free carbanion species. For example, the Grignard reagent methylmagnesium bromide (CH₃MgBr) functions as the equivalent of a methide ion (CH₃⁻). Because of this carbanion-like character, Grignard reagents are powerful nucleophiles and strong bases, allowing them to react with a wide variety of organic compounds, such as aldehydes, ketones, and esters, to form new carbon-carbon bonds.123