Synthese und Struktur der Vanadyl-, Cobalt(III)-, Nickel(II)-, Kupfer(II)-, Zink(II)- und PalIadium(II)-Komplexe eines vierzehngliedrigen ungesättigten Tetraazadibenzo-Makrocyclus / Synthesis and Structures of the Vanadyl, Cobalt(III), Nickel(II), Copper(II), Zinc(II) and Palladium(II) Complexes of a 14-Membered Unsaturated Tetraazadibenzo Macrocycle

Abstract

The synthesis and structural characterisation of complexes of the 14-membered macrocyclic trans-N4 dibenzo ligand 7,8,9,16,17.18-hexahydrodibenzo[e,l][1,4, 8.11]-tetraazacyclotetradecine (L1) is described. The crystal structures of six compounds were determined by single crystal X-ray diffraction. In [CuL1]2+ the metal atom is tightly bound within the macrocyclic cavity. The Cu-N bonds [201.2(3) and 191.8(3) pm] are rather short. Zn(II) is penta-coordinated in [Zn(L1)Cl]+ with the metal center outside the cavity. L1 is deprotonated at one or both secondary amine functions in the complexes [Ni(L1-H)]+, [Co(L1-2H)]+, [VO(L1-2H)] and [Pd(L1-2H)]. With the exception of [VO(L1-2H)] the metal ions assume nearly square planar N4-coordination, which is very rare for Co(III). Salts of [Co(L1-2H)]+ display a temperature independent magnetic moment of 0,64 B. M. The nickel, cobalt and palladium complexes show remarkably short metal-nitrogen bond distances: Ni-N [183.8(8)], Co-N [181.8(2)] and Pd-N [194.5(6) pm], respectively. The UV/Vis and EPR spectra, and the electrochemical behaviour of some of these complexes are also discussed.