SYNTHESIS AND COORDINATION CHEMISTRY OF MIDAZOL-2-YLMETHYL)-1,4,7,10-TETRAAZACYCLODODECANE

The potentially octadentate ligand midazol-2-ylmethyl)-1,4,7,10-terraa zacyclododecane (H2L), which contains two oxygen and two nitrogen dono rs on the groups attached to the macrocycle, has been isolated and cha racterized as the pentahydro-bromide or -perchlorate, H2L . 5HY (Y = B r 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 octah edral 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 meta l ions, in peripheral positions, are seven-co-ordinated, whereas the t hird is tetrahedrally four-co-ordinated.