Compartmental ligands. Part I. Mononuclear macrocyclic Schiff-base transition-metal complexes derived from 1,3,5-triketones

Abstract

A series of macrocyclic Schiff bases derived from 1,3,5-triketones and α,ω-alkanediamines has been prepared and their mononuclear complexes with Cu^II Ni^II and Co^II are described. The symmetrical macrocycles are derived from the reaction of heptane-2,4,6-, nonane-3,5,7-, undecane-4,6,8-, or 2,8-dimethylnonane-3,5,7-trione (2 mol) with ethane-1,2-, propane-1,2-, propane-1,3-, or butane-1,4-diamine (2 mol), in ethanol, and are potentially tetra-anionic ligands. Treatment of the pre-formed macrocycle with metal acetate, or a template reaction involving the triketone, diamine, and metal salt, gives the corresponding mononuclear transition-metal derivative. The complexes are characterised by their i.r., diffuse-reflectance, and mass spectra and room-temperature magnetic moments. Positional isomers of the copper(II) complex of the macrocycle derived from heptane-2,4,6-trione (2 mol), ethane-1,2-diamine (1 mol), and propane-1,2-dlamine (1 mol) are reported. Complexes of other unsymmetrical macrocycllc Schiff bases prepared by similar routes are described. The symmetrical macrocycle derived from heptane-2,4,6-trione and benzene-1,2-diamine is also reported.