Metal complexes of biologically important ligands, LXXVIII. Synthesis of palladium complexes of ferrocenyl-substituted amino acid derivatives

Abstract

Schiff bases from ferrocene aldehyde and α-amino acidates react with PdCl2 or Na2PdCl4 to give N,O-chelate complexes (2a–e, 3). The related N-ferrocenylmethylen-α-amino acid esters give, with Pd(OAc)2, cyclopalladated acetate-bridged complexes (4a,b). N,O-chelate complexes (5–7) are obtained from Na2PdCl4 with N-ferrocenylmethyl prolinate and-alaninate as well as with N,N-dibenzyl glycinate. The ethyl ester of N,N-dibenzylglycine and Pd(OAc)2 form the cyclopalladated acetate-bridged complex 8, while the ester of N-monobenzylglycine and Na2PdCl4 affords trans-PdCl2(L)2 with a monodentate N-coordinated ligand. The structures of 2a, 4a, 5, 7, and 9 were determined by X-ray diffraction. Keywords: ferrocene, amino acids, palladium(II) complexes, crystal structures.