Synthesis and crystal structure of trans-diaqua(1,4,8,11-tetraazaundecane)copper(II) isophthalate monohydrate

Abstract

In the title hydrated molecular salt, [Cu(C7H20N4)(H2O)2](C8H4O4)·H2O, the metal ion is coordinated by the two primary and two secondary N atoms of the amine ligand and the mutually trans O atoms of the water molecules in a tetragonally distorted octahedral geometry. The average equatorial Cu—N bond lengths (2.013 and 2.026 Å for Cu—Nprim and Cu—Nsec, respectively) are substantially shorter than the average axial Cu—O bond length (2.518 Å). The tetraamine ligand adopts its energetically favored conformation with its five- and six-membered chelate rings in gauche and chair conformations, respectively. In the crystal, the N—H donor groups of the tetraamine, the acceptor carboxylate groups of the isophthalate dianion and both the coordinated water molecules and the water molecule of crystallization are involved in numerous N—H...O and O—H...O hydrogen bonds, resulting in the formation of electroneutral layers oriented parallel to the ac plane.