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A s donor groups of functionalized tetraazamacrocycles change the properties of the metal ion when they coordinate, so the metal ion can modify the reactivity of the functional group. Examples of Cu(I1) promoted ester and nitrile hydrolysis in the complexes 2 5 have been studied kinetically. The mechanisms of the two reactions are probably different, the nitrile being hydrolyzed to the amide by an internal, the esters probably by an external OHattack. The X-ray structure of the C u ( I 1 ) complex with 5 clearly shows that the ester group is coordinated through its carbonyl oxygen to the metal ion, thus supporting the proposed external OH--attack. The second series o f examples show that i n the symmetrical Cu(I1) complexes 6 and 9 only one group can selectively be modified. These reactions are possible because of the special structure these macrocycles adopt in the trans-I ( R S R S ) configuration and because of the coordination of only one of the two groups. INTRODUCTION After the discovery of the complexation ability and selectivity of macrocycles (ref. I), these compounds have been modified in several ways i n order to obtain ligands with new properties. One direction of this development has been the introduction of functionalized side chains, attached to the macrocycle either at a carbon or a nitrogen atom, to increase the stability, to change the selectivity or modify the solubility of their complexes (ref. 2). In other cases the functional group of the side chain has been introduced to tune the properties o f the metal ion to which it coordinates. So, for example, one can shift in the Ni(I1) complex of 1 from a square planar, diamagnetic yellow species to an octahedral, paramagnetic blue one just by controlling the coordination of the amino side chain group through protonation or deprotonation of it (ref. 3 ) .

Metal ion effect on reactivity of pendant groups in functionalized macrocyclic complexes