NOVEL N,N'-METHYLENE-BRIDGED METAL(II) COMPLEXES OF N,N'-METHYLENEDI(4-HYDROXY-L-PROLINE) OBTAINED FROM THE CONDENSATION OF BIS(4-HYDROXY-L-PROLINATO)METAL(II) WITH FORMALDEHYDE

The condensation of bis(4-hydroxy-L-prolinato)metal(II) (metal = zinc, cobalt, copper, nickel) with formaldehyde led to the formation of the respective metal(II) complexes of N,N'-methylenedi(4-hydroxy-L-proline), M(II)[My(OH-Pro)(2)], each of which possesses an N,N'-methylene bridge linking the coordinated 4-hydroxy-L-proline ligands. Such linkage is without precedent in the products of the reactions of chelated amino acids with aldehydes.