Macrocyclic effect upon site-selective CuIIMII or MIICuII core formation with unsymmetric phenol-based macrocyclic ligands †

Abstract

Complexes of phenol-based dinucleating macrocycles, (L 2;2 ) 2Ϫ and (L 2;4 ) 2Ϫ , comprised of two 4-bromo-2iminomethyl-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;2 )][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 ؒ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.

Synthesis of Lateral Macrobicyclic Compartmental Ligands: Structural, Magnetic, Electrochemical, and Catalytic Studies of Mono- and Binuclear Copper(II) Complexes

“…Synthesis and characterization of novel phenoxo complexes are of main interest; these complexes are portals in the field of copper coordination chemistry and are at the meeting point of the two fields of molecular magnetism and macrocyclic compounds. − These phenoxo copper(II) complexes are the beacon in modeling, and they serve as bioinorganic model compounds not only in enzymatic reactions, but also in catalytic synthetic oxidation reactions. − Hence, binuclear copper(II) complexes are of interest for availing magnetostructural correlations and as useful model systems for catalysis. Several macromonocyclic complexes of ligands, containing ether oxygen and tertiary nitrogen, tertiary nitrogen, and phenolic oxygen as coordinating atoms, were reported in the literature . Only a few bicyclic systems have been studied so far .…”

“…Several macromonocyclic complexes of ligands, containing ether oxygen and tertiary nitrogen, tertiary nitrogen, and phenolic oxygen as coordinating atoms, were reported in the literature. 9 Only a few bicyclic systems have been studied so far. 10 Metal ions, together with ligands, contain a variety of structural information that has attracted attention in the field of supramolecular chemistry, because of the self-assembly reaction.…”

New Tetraaza Macrobicyclic Ditopic Receptors for Metal Ions: Synthesis, Redox Response and Kinetics of Phosphate Hydrolysis of Unsymmetrical Macrobicyclic Mono- and Binuclear Nickel(II) Complexes

“…These ligands are capable of forming symmetrical or dissymmetrical homo-and heterobinuclear complexes. Several macroyclic complexes of ligands containing ether oxygen and tertiary nitrogen, tertiary nitrogen and phenolic oxygen as coordinating atoms have been reported in the literature [10] but only a few bicyclic systems have been studied so far [11]. In the field of supramolecular chemistry [11,12], unsymmetrical compartmental metal ions together with ligands contain a variety of structural information that has drawn attention to the self-assembly and translocation processes.…”

Synthesis, crystal structures and spectroscopic properties of two novel oxamido-bridged trinuclear complexes [Cu2M] (M = Cu, Zn)

“…For macrocyclic ligands have a great advantage over non-cyclic ones: macrocyclic cores can be thermodynamically stabilized and kinetically retarded toward metal dissociation and substitution by the so-called ''macrocyclic effect'' [20,21] and the macrocyclic ligand may restrict the type of the complex formed [22,23]. So polymetallic complexes of macrocyclic ligands have been of great interest to supramolecular and coordination chemists for their special structure, properties and functionalities.…”