The infrared spectra of allyl-and methallyl-d2-magnesium bromides have two double bond streching bONds, corresponding to C CH2 and C CD2 groups in equilibrating allylic isomers. The methylene resonances in the 13C NMR spectra of allylmagnesium bromide and chloride and methallylmagnesium bromide are broadened at low temperatures by an exchange process which appears to be the interconversion between the classical ...