Metal-directed synthesis routes to a 16-membered tetraazamacrocycle with two pendant primary amine groups

The reaction of the bis(propane-1,3-diamine)copper(II) ion with paraformald ehyde and nitroethane in dry methanol under basic conditions produces a mac rocyclic product, (cis-3,11-dimethyl-3,11-dinitro-1,5,9,13-tetraazacyclohex adecane)copper(II) perchlorate, in low yield, compared with the good yield obtained in the parallel chemistry possible even under aqueous conditions u sing palladium(II) as a template. The palladium complex was reduced with zi nc amalgam in dilute aqueous acid to yield the metal-free 16-membered macro cyclic hexaamine, in this case re-complexed and characterised by an X-ray c rystal structure as the (cis-3,11-dimethyl-1,5,9,13-tetraazacyclohexadecane -3,11-diamine)copper(II) perchlorate. The copper ion is found in a tetragon ally elongated and trigonally-distorted octahedral environment, with all si x of the ligand nitrogens coordinated, the two primary amine pendant groups occupying cis sites. (C) 2000 Elsevier Science S.A. All rights reserved.