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

Complexes of phenol-based dinucleating macrocycles, (L-2;2)(2-) and (L-2;4) (2-), comprised of two 4-bromo-2-iminomethyl-6-methylaminomethylphenolate m oieties combined by an ethylene chain at the amino nitrogens and by an ethy lene or a 1,4-tetramethylene chain at the imino nitrogens, have been prepar ed: mononuclear [Cu(L-2;2)] and [Cu(L-2;4)], and dinuclear [PbCu(L-2;2)][Cl O4](2) and [PbCu(L-2;4)][ClO4](2). The reaction of [Cu(L-2;2)] and [Cu(L-2; 4)] with MCl2 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 si gnificant antiferromagnetic interaction within each dinuclear unit. The rea ction of [PbCu(L-2;2)][ClO4](2) with MSO4 salts formed dinuclear (CuMII)-M- II perchlorate complexes [CuM(L-2;2)][ClO4](2) (M = Co, Ni, Cu or Zn). A si milar transmetallation for [PbCu(L-2;4)][ClO4](2) caused a scrambling of th e metal ions. A crystallographic study of [CuNi(L-2;2)(dmf)][ClO4](2). MeOH indicates that the Cu-II migrates from the iminic to the aminic site to ac commodate the Ni-II in the iminic site. Kinetic and thermodynamic effects o f the macrocycles upon the site selectivity for the metal ions are discusse d.