Nickel(II), Copper(II), and Zinc(II) Complexes of Penta-azamacrocyclic Ligands. Crystal and Molecular Structure of 3,6,9,12-Tetramethyl-3,6,9,12,18-penta-azabicyclooctadeca-1(18),14,16-trienezinc(II) Perchlorate

Article abstract of DOI:10.1039/DT9870002643

The three related penta-azamacrocyclic ligands 6,9-dimethyl-2,13-dioxo-3,6,9,12,18-penta-azabicyclo<12.3.1>octadeca-1(18),14,16-triene (L¹), 6,9-dimethyl-3,6,9,12,18-penta-azabicyclo<12.3.1>octadeca-1(18),14,16-triene (L²), and 3,6,9,12-tetramethyl-3,6,9,12,18-penta-azabicyclo<12.3.1>octadeca-1(18),14,16-triene (L³), have been prepared.The complexes 2 (dmso = dimethyl sulfoxide; L = L², M = Ni or Zn; L = L³, M = Ni) and 2 (L = L², M = Cu; L = L³, M = Cu or Zn) have been isolated.The Ni²⁺ complexes are high-spin and six-co-ordinate, and the Cu²⁺ complexes five-co-ordinate. 13C N.m.r. spectroscopy shows 2)(dmso)>2 to be a 2:1 mixture of two species, one symmetric and the other asymmetric, whilst in 3)>2 only ca. 10 percent of the asymmetric species is present in nitromethane solution.X-Ray crystallography has been used to determine the structure of the symmetric isomer of 3)>2 /= 3.0> diffractometer collected reflections>; it reveals distorted trigonal-bipyramidal geometry about the zinc ion, and an approximate C₂ rotation axis passing through the zinc and pyridine N atoms, and bisecting the macrocyclic C-C bond furthest removed from the pyridine ring .

Full text of DOI:10.1039/DT9870002643

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