SYNTHESIS AND PROPERTIES OF A TETRAAZA MACROCYCLIC LIGAND CONTAINING 2-PYRIDYLMETHYL PENDANT ARMS AND ITS COPPER(II) AND NICKEL(II) COMPLEXES - CRYSTAL-STRUCTURE OF THE COPPER(II) COMPLEX

A new functionalized macrocyclic ligand 2,13-bis(2'-pyridylmethyl)-5, 16-dimethyl-2,6, 3,17-tetraazatricyclo[16.4.0.O-1.18(7.12)]docosane (L -2) containing two 2-pyridylmethyl pendant arms has been prepared by t he one-step reaction of 3,4-dimethyl-2,6, 13,17-tetraazatricyclo[ 16.4 .0.O-1.18(7.12)]docosane (L-1) with 2-(chloromethyl) pyridine. The oct ahedral complexes [NiL2](ClO4)(2) and [CuL2](ClO4)(2), in which two py ridyl groups are coordinated to the metal ion, have been prepared and characterized. The crystal structure of [CuL2](ClO4)(2) shows that the complex is centrosymmetric and the metal center has a tetragonally di storted octahedral geometry. In concentrated HClO4 solutions, the coor dinated pyridyl groups of [CuL2](2+) are protonated and are removed fr om the coordination sphere. However, those of [NiL2](2+) are not proto nated but are coordinated to the metal ion even in 3.0M HClO4. The mac rocycle L-2 reacts more slowly with copper(II) ion than does L-1. (C) 1998 Elsevier Science Ltd. All rights reserved.