Complexes of ligands providing endogenous bridges. Part 5. Solution studies on a novel ‘3 + 3’ hexamine Schiff-base macrocyclic complex of lanthanum

Abstract

Structural studies in solution show that when lanthanum nitrate is used as a template in the reaction of 2,6-diacetylpyridine and 1,3-diamino-2-hydroxypropane a ‘3 + 3’ macrocycle containing three lanthanum ions is the predominant species formed. Hydrogen-1 n.m.r. decoupling and n.O.e. difference spectroscopy confirms the presence of a two-fold axis of symmetry where two ‘sides’ of the macrocycle are identical and different from the third.