Crystal structure of trans-diaqua(3,10-dimethyl-1,3,5,8,10,12-hexaazacyclotetradecane)copper(II) pamoate

The asymmetric unit of the title compound, trans-diaqua(3,10-dimethyl-1,3,5,8,10,12-hexaazacyclotetradecane-κ4N1,N5,N8,N12)copper(II) 4,4′-methylenebis(3-hydroxynaphthalene-2-carboxylate), [Cu(C10H26N6)(H2O)2](C23H14O6) {[Cu(L)(H2O)2](pam), where L = 3,10-dimethyl-1,3,5,8,10,12-hexaazacyclotetradecane and pam = dianion of pamoic acid} consists of two independent halves of the [Cu(L)(H2O)2]2+ cation and one dicarboxylate anion. The CuII atoms, lying on inversion centres, are coordinated by the four secondary N atoms of the macrocyclic ligands and the mutually trans O atoms of the water molecules in a tetragonally elongated octahedral geometry. The average equatorial Cu—N bond length is significantly shorter than the average axial Cu—O bond length [2.007 (10) and 2.486 (18) Å, respectively]. The macrocyclic ligand in the complex cations adopts the most energetically stable trans-III conformation. The complex cations and anions are connected via hydrogen-bonding interactions between the N—H groups of the macrocycles and the O—H groups of coordinated water molecules as the proton donors and the O atoms of the carboxylate as the proton acceptors into layers lying parallel to the (1\overline{1}1) plane