A general and very straightforward route to the selective N-functionalization of 1,4,7-triazacyclononane with imidazole groups. Crystal structure determinations of nickel(II), copper(II) and zinc(II) complexes

An easy, one-step procedure for the synthesis of the selectively substituted macrocycles 1-(1-methylimidazol-2-ylmethyl)-1,4,7-triazacyclononane, L1, and 1,4-bis(1-methylimidazol-2-ylmethyl)-1,4,7-triazacyclononane, L2, is reported. The potentially tetra-, L1, and pentadentate, L2, compounds yield nickel(II), copper(II) and zinc(II) complexes which have been isolated in the solid state. The crystal structures of [NiL1(N3)]2[PF6]2 (1), [Cu2L2 1(OH)][PF6]3 (2), [ZnL1Cl]BPh4 (3), [NiL2(H2O)][BPh4]2·C2H5OH (4) and [Ni2L2 2(N3)][PF6]3 (5) have been determined by X-ray diffraction studies. The L1 and L2 molecules provide four and, respectively, five nitrogens for complexation of the metal ions whose coordination requirements are completed by additional ligands either terminal (Cl, H2O, compounds 3 and 4) or bridging two metal ions (N3 −, compounds 1 and 5; OH−, compound 2). In its complexes nickel(II) is six-coordinated in an approximately octahedral environment. Both copper(II) and zinc(II) are five-coordinated with geometries approximately square pyramidal and, respectively, trigonal bipyramidal.