engleski

Zn(II) and Cu(II) complexes of chiral iminodiacetamide ligands

Tridentate ligands, such as iminodiacetamide derivatives and transition metals can form hexacoordinated complexes of ML and ML2 stoichiometry1. Ligands imda-pea and imda-phe prepared in this work have chiral chains with amide groups (pea = (S)-1-phenylethanamine and phe = L-Phenylalanine methyl ester) that could form hydrogen bonds between two ligands in a complex of ML2 stoichiometry. For the ligand imda-pea, one hydrogen bond is possible, while two hydrogen bonds are possible for imda-phe, allowing the formation of different secondary structures. These compounds could have potential use in enantioselective catalysis. In complexes with hydrogen bonded secondary structures, chirality can be transmitted to the metal centre by ''backdoor induction'' from distant chiral groups, and the metal centre can selectively catalyze enantioselective reactions2. In this work, ligands imda-pea and imda-phe were prepared in two steps, by standard amide coupling reactions, followed by nucleophilic substitution with chloroacetamide precursors. The complexes were characterized in solid state by IR spectroscopy. In solution, the Zn(II) complexes were studied by 1H NMR spectroscopy and the Cu(II) complexes by UV-Vis spectroscopy. The transfer of chirality to the metal centre was studied by CD spectroscopy.

tridentate ligands ; hydrogen bonds ; geometrical isomers

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