Nickel(II) and copper(II) complexes of macrocyclic and acyclic Schiff-base ligands derived from new asymmetrical tripodal tetraamines and 2,6-diacetylpyridine

Abstract

The asymmetrical tripodal 4,2,2′-tetraamine N{(CH2)4NH2}{(CH2)2NH2}2 bee, 3,2,2′-tetraamine N{(CH2)3NH2} {(CH2)2NH2}2 pee, and 3,3′,2-tetraamine N{(CH2)3NH2}2{(CH2)2NH2} ppe ligands have been prepared. In the presence of CuII or NiII ions, these ligands condense with 2,6-diacetylpyridine. In some cases, cyclization occurs and new isomers of CR-type with a pendant primary amine group are formed. In the other cases ring closure does not occur and coordinated acyclic hexadentate ligands have been isolated. At room temperature and in absolute methanol the latter acyclic complexes are usually the only products. I.r., u.v.–vis., reflectance spectra and magnetic moments for the complexes were recorded.