Studies of pendant arm macrocyclic ligands. Part 7. Synthesis of two sexidentate macrocycles based upon a pyridine-containing tetra-aza macrocycle with either two 2-pyridylmethyl or two 1-pyrazolylmethyl pendant co-ordinating arms, and characterisation of their cobalt(II), nickel(II), copper(II), and zinc(II) complexes. Crystal structure of {3,11-di(2-pyridylmethyl)-3,7,11,17-tetra-azabicyclo[11.3.1]heptadeca-1(17),13,15-triene}nickel(II) perchlorate

Two new sexidentate macrocycles, 3,11 -di(2-pyridylmethyl)-3,7,11,17-tetra-azabicyclo[11.3.1]heptadeca-1(17),13,15-triene(L1) and 7-methyl-3,11-di-(1-pyrazolylmethyl)-3,7,11,17-tetra-azabicyclo[11.3.1]heptadeca-1(17),13,15-triene (L2), have been prepared and characterised, together with their metal complexes of formula [M(L)][ClO4]2(M = Co, Ni, Cu, or Zn; L = L1 or L2). An X-ray crystal structure of [Ni(L1)][ClO4]2 shows the nickel to be six-co-ordinate, with the macrocycle in a folded conformation, and with the two pendant 2-pyridylmethyl arms occupying cis co-ordination sites.