Addition to a carbonyl group

Organolithium addition   Grignard addition

Click the images to view the 3D animations for the two different organometallic reactions

Organolithium reagent

Lithium and magnesium are very electropositive metals. The Li-C or Mg-C bonds in organolithium or organomagnesium reagents are highly polarized towards carbon.

(Red represents areas which are electron rich, blue represents areas that are electron poor)

Grignard reagent

Organometallics are therefore very powerful nucleophiles, and attack at the carbonyl group to give alcohols, forming a new C-C bond. The reactions from these two classes of organometallic reagents with carbonyl compounds, are among the most important ways of making carbon-carbon bonds.