High-resoln. 13C NMR spectra of terminally monodeuterated alkali metal and alk. earth metal allyl compds. confirm earlier structure assignments: allylmagnesium bromide exists in a s-covalent structure, which rapidly and reversibly goes over into its metallomeric mirror-image; allyllithium forms a distorted p-complex; allylpotassium and allylcesium have the shape of perfectly sym. or slightly asym. p-complexes. No NMR spectroscopic evidence is found in THF soln. for the presence of aggregates and mixed aggregates resulting from dimerization or oligomerization of monomeric allylmetal species. [on SciFinder (R)]