Notes. Dicopper(II) complexes of an N6O2 macrocycle and seven-co-ordinate manganese(II), iron(II), cobalt(II), nickel(II), copper(II), and zinc(II) complexes of its N5O2 open-chain precursor

Abstract

The syntheses, via metal-ion (Mg²⁺, Ca²⁺, or Ba²⁺) template methods followed by transmetallation, of the complexes [ML¹]X₂(M = Mn^II, Fe^II, Co^II, Ni^II, Cu^II, or Zn^II; X = ClO₄^– or BPh₄^–) of the potentially septidentate ligand L¹ formed by condensation of 1 mol of 2,6-diacetylpyridine with 2 mol of 3-oxapentane-1,5-diamine is described. The collective evidence of the properties (magnetic and spectroscopic) of the complexes indicates a seven-co-ordinate (pentagonal-bipyramidal) structure. Ring closure, via a transamination mechanism, of L¹ in BaL¹(ClO₄)₂ leads to the complex BaL²(ClO₄)₂·3H₂O containing the 24-membered N₆O₂ macrocyclic ligand L². The single Ba²⁺ in this complex may be replaced by two copper(II) ions to afford the binuclear complex Cu₂L²(ClO₄)₄·H₂O which on treatment with imidazole (Him) gives Cu₂L²(im)(ClO₄)₃·H₂O containing an imidazolate bridge between the antiferromagnetically coupled metal centres.