Studies of pendant-arm macrocyclic ligands. Part 8. Synthesis of two pentaazamacrocycles based upon pyridine-containing tetraazamacrocycles with a single pendant co-ordinating 2-pyridylmethyl arm, and characterisation of their nickel(II), copper(II) and zinc(II) complexes. Crystal structure of 7-(2′-pyridylmethyl)-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-trienezinc(II) tetrafluoroborate

Abstract

Two new quinquedentate pentaazamacrocycles, 7-(2′-pyridylmethyl)-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene L¹ and its 3,11-dimethyl derivative L², have been characterised, together with their metal complexes of formulae [ML(OH₂)][BF₄]₂(M = Ni or Cu) and [ZnL][BF₄]₂(L = L¹ or L²). The crystal structure of [ZnL¹][BF₄]₂ shows a distorted square-pyramidal geometry, with the Zn 0.59 Å above the plane of the macrocyclic ring in the direction of the pendant co-ordinated pyridyl group.