Studies on the metal-amide bond. XIV. The coordination chemistry of N-methyl-N,N′-bis(2′-pyridinecarboxamide)-1,2-ethane; a potentially tetradentate ligand containing both secondary and tertiary amide groups

The isolation and characterization of a number of transition metal complexes of the ligand N-methyl-N,N′-bis(2′-pyridinecarboxamide)-1,2-ethane, bpen-MeH, is described. Representive non-deprotonated 1:1 complexes of bivalent cobalt, nickel copper and zinc show the ligand to act as a bis-bidentate, forming five- or six-coordinate polymeric complexes involving coordination through pyridyl nitrogen and amide oxygen atoms. The complexes Cu₂(bpenMeH)Cl₄ and Ni₂(bpenMeH)₃(ClO₄)₄·7.5H₂O also demostrate this mode of bonding by the ligand. One complex alone of bivalent palladium. was obtained in which coordination of the deprotonated secondary-amide nitrogen atom occurs. Coordination of the tertiary-amide nitrogen atom is not observed for any of the complexes.