STUDIES OF PENDANT-ARM MACROCYCLIC LIGANDS .8. SYNTHESIS OF 2 PENTAAZAMACROCYCLES BASED UPON PYRIDINE-CONTAINING TETRAAZAMACROCYCLES WITH A SINGLE PENDANT COORDINATING 2-PYRIDYLMETHYL ARM, AND CHARACTERIZATION 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

Two new quinquedentate pentaazamacrocycles, 7-(2'-pyridylmethyl)-3,7,11,17-tetraazabicyclo-[11.3.1]heptadeca-1(17),13,15-tr iene 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 angstrom above the plane of the macrocyclic ring in the direction of the pendant co-ordinated pyridyl group