Trinuclear Cu(ii) complexes of a chiral N₆O₃amine

Abstract

Enantiopure trinuclear Cu(II) complexes 3 and 4 of macrocyclic amine 1 derived from the 3 + 3 condensation of 2,6-diformyl-4-methylphenol and (1S,2S)-1,2-diaminocyclohexane have been synthesized and characterized by ESI MS and NMR spectroscopy. The X-ray crystal structures of both complexes have been determined. The structure of the chloride derivative 3 indicates unusual combination of distorted tetragonal bipyramidal, square pyramidal and square geometries of the three Cu(II) ions bound by macrocycle 1. The acetate complex 4 also exhibits unsymmetrical trinuclear core with the bridging and terminal acetate anions. The complexation of Cu(II) ions by macrocycle 1 has been studied using potentiometric methods and both protonation and binding constants of 1 have been determined. The distribution of the complex forms indicates cooperative binding of three metal ions by 1. The overall magnetic behaviour for 3 corresponds to an antiferromagnetically coupled triangular system. Compound 4 shows the presence of antiferromagnetic coupling (J = -74.9(1) cm(-1)) between the metal centers in equilateral triangular array.

Synthesis, structure, magnetism, and hydrolase and catecholase activity of a new trinuclear copper(II) complex

“…In fact, trinuclear copper(II) complexes with trigonal symmetry have attracted attention as magnetic materials and systems mimicking trinuclear metalloenzyme sites present in copper oxidases, such as ascorbate oxidase, ceruplasmin and laccase [3]. One of the forms of the copper oxidases corresponds to an antiferromagnetically coupled trinuclear Cu(II) cluster [4].…”

Enantioselective Self‐Assembly of Triangular Dy3 Clusters with Single‐Molecule Magnet Behavior

“…The core of triangular Ln 3 is bound in the central N 6 O 3 (three phenolic oxygen atoms and six neighboring amine nitrogen atoms) of macrocyclic ligand. Thus, the ligand has a more flatter, helically twisted conformation than that observed in the free form and in its previously reported trinuclear transition metal complexes,13c, 15 due to the presence of μ 3 ‐OH and large ionic radius of lanthanide ions. The coordination spheres of Ln1 and Ln2 are completed by two SCN − anions in axial positions on opposite sides of the macrocycle, while Ln3 is completed by two H 2 O molecules.…”

Structural studies of diaminocyclohexane-containing aza-crown ether macrocycles and their Zn(II) complexes

“…The Zn(II) ion was chosen because it is kinetically labile, oxidatively stable, has a high affinity for amine ligands, and is amenable to study by NMR. While metal complexes of non-macrocyclic N-benzylated DACH ligands have been widely employed in enantioselective catalysis [25][26][27] and elsewhere [28][29][30], and numerous polynuclear DACH-derived macrocyclic metal complexes are known [3,[31][32][33]; mononuclear macrocyclic metal complexes which may be capable of coordinating guest molecules within their interior cavities are potentially very attractive as supramolecular receptors and have been less well studied [34].…”