Grignard reagents are a class of organomagnesium compounds formed by reacting alkyl or aryl halides with magnesium metal. They are typically represented as R-MgX, where R is an organic group and X is a halogen. These reagents are highly reactive and are used in organic synthesis to form carbon-carbon bonds. When Grignard reagents react with carbonyl compounds, they can produce alcohols through nucleophilic addition. This makes them valuable in the synthesis of various organic molecules, including pharmaceuticals and complex natural products. Their ability to react with a wide range of electrophiles is a key feature in organic chemistry.