Multidentate chelating agents from Quinoline-8-aldehyde. I. Tridentate and quadridentate Schiff bases from primary diamines

Abstract

Complexes of 1,2-bis(8-quinolylmethyleneimino)ethane with cobalt(II), nickel(II), and copper(II) are described. The copper complexes are five-covalent and, it is suggested, trigonal bipyramidal. Reaction of the Schiff base with iron(II), cobalt(III), and, under certain conditions, nickel(II) leads to its partial hydrolysis, and complexes of the tridentate 1-amino-2-(8-quinolylmethyleneimino)ethane are obtained. The hydrolysis of the Schiff base in the presence of metal ions is discussed in terms of steric effects within the base and of the stereochemical demands of the metal ions. Complexes of 1,2-bis(8-quinolylmethyleneimino)benzene and its hydrolysis derivative 1-amino-2-(8-quinolylmethyleneimino)ethane are also described.