Synthesis and co-ordination chemistry of 1,7-bis(carboxymethyl)-4,10-bis(1-methylimidazol-2-ylmethyl)-1,4,7,10-tetr aazacyclododecane

摘要

The potentially octadentate ligand 1,7-bis(carboxymethyl)-4,10-bis(1-methylimidazol-2-ylmethyl)-1,4,7,10-terr aazacyclododecane (H2L), which contains two oxygen and two nitrogen donors on the groups attached to the macrocycle, has been isolated and characterized as the pentahydro-bromide or -perchlorate, H2L . 5HY (Y = Br or ClO4). Its co-ardination chemistry towards nickel(Ir) and zinc(II) ions has been investigated and the structures of the complexes which have been obtained, [NiL].6.5H(2)O 1, [Ni(H1.5L)][ClO4](1.5).2H(2)O 2 and [Zn3L2][ClO4](2).5H(2)O 3, have been determined by single-crystal X-ray analyses. The metal ion in 1 and 2 is in an approximately octahedral environment formed by the four nitrogen donors of the macrocycle and two donors from the dangling groups, either carboxyl oxygens 1 or methylimidazole nitrogens 2. In the trimetallic zinc complex two metal ions, in peripheral positions, are seven-co-ordinated, whereas the third is tetrahedrally four-co-ordinated. [References: 55]