Komplexe zweier vierzehngliedriger Tetraazadibenzo-Makrocyclen. Strukturen eines freien Liganden und von Nickel(II)-, Kupfer(II)- und Zink(II)-Komplexen / Complexes of Two 14-Membered N4 Dibenzo Macrocycles. Crystal Structures of a Free Ligand and of Nickel(II), Copper(II) and Zinc(II) Complexes
The syntheses and structural characterizations of complexes of two 14-membered macrocyclic trans-N4 dibenzo ligands, 5,7,8,9,14,16,17,18-octahydrodibenzo[e,1]-[1,4,8,11-tetraazacyclotetradecine- 6,15-dimethyl (L3) resp. -6,15-diacetamide (L4), are presented. The crystal structures of five compounds have been determined by single crystal X-ray diffraction. The free ligand L3 has a saddle-shaped structure with intramolecular hydrogen bonds. This conformation of the ligand exists also in the Zn(II) complex in which the metal ion is five-coordinated with the metal center outside the cavity. The coordination polyhedron is intermediate between a trigonal bipyramid and a square pyramid. In cis-[Ni(L3)(NCS)2] the ligand is folded along an N ⋯ N axis. The nickel ion in this complex shows an approximate octahedral geometry. For Ni(II) and Cu(II) complexes of ligand L the overall geometry is also distorted octahedral. The folding of the ligand causes a cis-N4O2 coordination.