An alternating chain consisting of dinuclear Cu(II) ions bridged by bonded end-on bis(μ-dicyanamido-κNI,N5) ligands and hydrogen-bonded pairs of bis(pyrimidin-2-yl)amines, with unusually long Cu•••Cu distances of 7.20 and 9.99 Å:: Synthesis, structure and magnetic properties of [Cu(dipm)(μ-dca)(H2O)(ClO4)]2•2EtOH

A novel bis (end-to-end) bridged dicyanamide dinuclear copper(II) compound with the general formula [Cu(dipm)(mu-dca)(H2O) (ClO4)](2) center dot 2EtOH (in which dipm = bis(pyrimidin-2-yl)amine) has been synthesised and characterised by X-ray crystallography and infrared spectroscopy. In addition, EPR and magnetic measurements have been performed. The geometry around the copper(II) ion is distorted octahedral with the basal plane formed by the two nitrogen atoms of the dipm ligand and two nitrogen atoms of two end-to-end bridging dca anions. The Cu-N distances vary from 1.979(4) to 2.004(3) angstrom. The apical positions are occupied by an oxygen atom of a water ligand with a Cu-O distance of 2.216(3) angstrom and an oxygen atom of a perchlorate anion with a semi-coordinating distance of 2.89(1) angstrom, 2.950(7) angstrom. A hydrogen-bond interaction of the Watson-Crick type is observed between the amine N atom of a dipm ligand to a pyrimidyl N atom of a neighbouring dipm ligand with a N... N distance of 2.970(4) angstrom. Furthermore, medium to strong hydrogen bond interactions are present between oxygen atoms of the water molecule, perchlorate lattice anions and ethanol molecules. The magnetic interaction between the Cu-Cu atoms is weak antiferromagnetic with a singlet-triplet separation (J) of -4.3 cm(-1). (c) 2007 Elsevier B.V. All rights reserved.