A systematic study of the effect of chloride ions on the NMR characteristics of several cationic diphosphine η 3-allyl palladium complexes has revealed in some instances a deshielding of the protons. Chloride ions also enhance the reactivity of the complexes. Thus 〚(Me-Duphos)(1,3-diphenylallyl)palladium〛chloride leads mostly to 〚(Me-Duphos)dichloropalladium〛 and to chalcone at room temperature, whereas at low temperature a pair of cationic and anionic allyl palladium complexes is obtained.