Synthesis of pyridine-containing tetra-aza macrocycles: 3,7,11,17-tetra-azabicyclo[11.3.1]heptadeca-1(17),13,15-triene (L1), its 3,11-dibenzyl (L2) and 3,7,11-tribenzyl (L3) derivatives, and their nickel(II), copper(II), and zinc(II) complexes: crystal structures of L2·HCL and [Ni(L2)Cl]ClO4·H2O

Abstract

Three pyridine-containing 14-membered-ring tetra-aza macrocycles, 3,7,11,17-tetra-azabicyclo-[11.3.l]heptadeca-1(17),13,15-triene (L¹), its 3,11-dibenzyl (L²) and 3,7,11-tribenzyl (L³) derivatives, and their metal complexes with Ni²⁺, Cu²⁺, and Zn²⁺ have been prepared and characterised. The structure of [Ni(L²)Cl] ClO₄·H₂O has been established by X-ray crystallography. The Ni²⁺ ion co-ordination is approximately square pyramidal, with the macrocycle folded about an axis defined by the two N–CH₂Ph groups, the secondary amine group co-ordinated at the apex of the square pyramid, and the chloride ion in the basal plane along with the other three N-donor atoms (Cl^– in a trans position to the pyridine N atom). The crystal structure of L²·HCl is also reported.