THE EFFECT OF N2-MONOMETHYLATION AND DIMETHYLATION ON THE CRYSTAL-STRUCTURES OF BIS[(S)-PHENYLALANINAMIDATO]COPPER(II) COMPLEXES

(S)-phenylalaninamide, N2-methyl-(S)-phenylalaninamide, and N2,N2-dime thyl-(S)-phenylalaninamide co-ordinate to copper(II) as amidates, givi ng rise to trans bis(phenylalaninamidato) copper(II) complexes CuL2H-2 respectively (1), (2), and (3). Their crystal structures were determi ned by X-ray crystallography. The striking feature is that in bis[N2-m ethyl-(S)-phenylalaninamidato]copper(II) complex (2), both methyl grou ps are on the axial positions and on the same side of the co-ordinatio n plane. The knowledge of the crystal structures of complexes (1), (2) , and (3) which are used successfully as chiral selectors in HPLC (rev ersed phase), provides very useful information on the stereochemical f eatures of enantioselective species.