The N,O-chelates M(3,4-dehydro-D,L-prolinate)2 (M = Ni, Cu) have been obtained from Ni(OH)2 or Cu(OH)2 and the amino acid. The complexes (R3P)(Cl)M(α-aminoacidate) (M= Pd, Pt) have been synthesized from the chloro bridged compounds (R3P)(Cl)M(μ-Cl)2M(PR3)Cl (M = Pd, Pt; R = Et, n-Bu, Ph) and the potassium salts of the α-amino acids D,L-serine, D,L-threonine, 3,4-dehydro-D,Lproline and 4-hydroxy-L-proline. According to the 31P NMR and 13C NMR spectra the complexes with serinate and threoninate are formed as mixtures of cis/trans N-M-P isomers, whereas for the palladium complexes with 3,4-dehydroprolinate and 4-hydroxyprolinate a single isomer is observed