Synthesis and Structures of Copper(II) Complexes with Tetraaza Macrocycles

Abstract

Three new copper(II) complexes with the composition [Cu(L1)](H2O)2][Cu2(L1)2(µ-btc4-)]·2ClO4·6H2O·1.454CH3CN (1), [Cu(L1)(H2O)]·(muco2-)·(H2O)4 (2), [Cu(L2)(H2O)]·(muco2-)·(H2O)7 (3) (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14.4.01.18.07.12]docosane, H4btc = 1,2,4,5-benzenetetracarboxylic acid, H2muco = trans,trans-muconic acid) have been synthesized and structurally characterized by a combination of analytical, spectroscopic and X-ray crystallography. In (1), two different copper(II) coordination geometries, a five-coordinate square pyramid as well as an axially elongated six – coordinate octahedron, and (2), (3) have a similar structures, but different arrangements, are observed. In all complexes various types of hydrogen bonding interactions play an important role in determining the shapes of structural geometries, respectively.

The new Copper(II) complex, [Cu(L1)(H2O)2][Cu2(L1)2(µ-btc4-)]∙2ClO4∙6H2O∙1.454CH3CN (1) (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14.4.01.18.07.12]docosane, H4btc = 1,2,4,5-benzenetetracarboxylic acid) was prepared by the reaction of [Cu(L)](ClO4)2 and btcH4 in DMF/H2O/CH3CN/NEt3. The complex 1 was characterized by a combination of analytical, spectroscopic techniques. In addition, molecular structure was determined by single crystal X-ray diffraction methods. In 1, two different copper(II) coordination geometries, a five-coordinate square pyramid as well as an axially elongated six-coordinate octahedron, are observed. The btc4- ligand bridges two copper(II) macrocycles to form a dimer where all the hydrogen atoms of H4btc were deprotonated, forming a complex dianion. Additional copper(II) macrocycle involves in 1 in which two aqua ligands interact with central metal ion weakly, resulting in the formation of complex dication. Thus, the whole complex 1 is charge balanced.

Two new macrocyclic copper(II) supramolecules,[Cu(L1)(H2O)]·(muco2-)·(H2O)4 (2), [Cu(L2)(H2O)]·(muco2-)·(H2O)7 (3) (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14.4.01.18.07.12]docosane, H2muco = trans,trans-muconic acid) have been synthesized and structurally characterized by a combination of analytical, spectroscopics and X-ray crystallography. In 2 and 3 the structures exhibit 1D supramolecular chain containing copper(II) macrocycles which coordinated axially by one aqua ligand, uncoordinated muco2- and water molecules, respectively, where the 1D chains are interconnetcted through hydrogen bonds by the mediation of lattice water molecules to form 2D supramolecules. Although complexes 2 and 3 show similar structures, the arrangement in which formed 1D chain are different. The introduction of diastereomerically related macrocycles L1 and L2 is believed to cause different arrangement in 2 and 3.