Macrocyclic effect upon site-selective Cu~(II)M~(II) or M~(II)Cu~(II) core formation with unsymmetric phenol-based macrocyclic ligands

摘要

Complexes of phenol-based dinucleating macrocycles, (L~(2;2))~(2-) and (L~(2;4))~(2-), comprised of two 4-bromo-2-iminomethyl-6-methylaminomethylphenolate moieties combined by an ethylene chain at the amino nitrogens and by an ethylene or a 1,4-tetramethylene chain at the imino nitrogens, have been prepared: mononuclear [Cu(L~(2;2))] and [Cu(L~(2;4))], and dinuclear [PbCu(L~(2;2))][ClO_4]_2 and [PbCu(L~(2;4))][ClO_4]_2. The reaction of [Cu(L~(2;2))] and [Cu(L~(2;4))] with MCl_2 salts formed dinuclear [MCu(L~(2;2))Cl_2] and [MCu(L~(2;4))Cl_2] (M = Mn, Co, Ni, Cu or Zn), respectively. A crystallographic study of [NiCu(L~(2;2))Cl_2] indicates the Ni~(II) to reside in the aminic site and the Cu~(II) in the iminic site. The complexes, except for that of M = Zn~(II), show a significant antiferromagnetic interaction within each dinuclear unit. The reaction of [PbCu(L~(2;4))][ClO_4]_2 with MSO_4 salts formed dinuclear Cu~(II)M~(II) perchlorate complexes [CuM(L~(2;2))][ClO_4]_2 (M = Co, Ni, Cu or Zn). A similar transmetallation for [PbCu(L~(2;4))][ClO_4]_2 caused a scrambling of the metal ions. A crystallographic study of [CuNi(L~(2;2))(dmf)][ClO_4]_2 (centre dot) MeOH indicates that the Cu~(II) migrates from the iminic to the aminic site to accommodate the Ni~(II) in the iminic site. Kinetic and thermodynamic effects of the macrocycles upon the site selectivity for the metal ions are discussed.