SYNTHESIS AND COORDINATION CHEMISTRY OF THE PYRIDYL PENDANT-ARM AZAMACROCYCLES 1-(2-PYRIDYLMETHYL)-1,5,9-TRIAZACYCLODODECANE L(1) AND 1-(2-PYRIDYL-2'-ETHYL)-1,5,9-TRIAZACYCLODODECANE L(2), WITH NICKEL(II), COPPER(II) AND ZINC(II) - CRYSTAL-STRUCTURES OF [NI(L(1))(O2NO)]NO3 AND [ZNL(2)][ZN(NO3)(3.67)CL-0.33]

The azamacrocyclic ligands 1-(2-pyridylmethyl)-1,5,9-triazacyclodod L( 1) and 1-(2-pyridyl-2'-ethyl)-1,5,9-triazacyclododecane L(2) have been prepared, and their complexes with hydrated nickel(II). copper(ir) an d zinc(II) nitrates have been isolated. The nickel(II) complexes are h igh spin and six-co ordinate, whilst C-13 NMR spectroscopy shows that [ZnL(1)(OH2)](2+) exists as a symmetric trigonal-bipyramidal isomer in solution, and [ZnL(2)](2+) exists as a 2:1 mixture of tetrahedral and asymmetric trigonal-bipyramidal isomers. X-Ray crystallography has be en used to determine the solid-state structures of the octahedral [NiL (1)(O2NO)](+), and the tetrahedral isomer of [ZnL(2)](2+).