Laboratory preparation involves treating bromobenzene with magnesium metal, usually in the form of turnings.

Coordinating solvents such as ether or THF, are required to solvate (complex) the magnesium(II) center.

The solvent must be aprotic since alcohols and water contain an acidic proton and thus react with phenylmagnesium bromide to give benzene.

Carbonyl-containing solvents, such as acetone and ethyl acetate, are also incompatible with the reagent.Although phenylmagnesium bromide is routinely represented as C6H5MgBr, the molecule is more complex.

The compound invariably forms an adduct with two OR2 ligands from the ether or THF solvent.