Abstract

The nitrosyl cyanide Cu(en)₂Fe(CN)₅(NO) was prepared by the reaction of Cu(en)₂Cl₂ and Na₂ [Fe(CN)₅(NO)].2H₂O in aqueous solution. Single-crystal X-ray structure analysis revealed that the complex assumes a cyanide-bridged chain structure in which iron(II) is coordinated by five cyanide ligands and a nitrosyl group, and copper(II) is coordinated by two ethylenediamine ligands and two bridging cyanide ligands. The copper centres display a typical Jahn–Teller distortion characteristic of octahedral copper complexes with bond distance deviations in lattice symmetry from octahedral ideality: Cu-N(equatorial, mean) 2·010(3) Å and Cu-N(axial, mean) 2·569(3) Å. Infrared and ultraviolet studies shed light on the above molecular structure. A magnetic investigation showed the presence of a weak antiferromagnetic interaction (J = -1·06 cm^-1) between the copper atoms within each chain through the diamagnetic Fe(CN)₅(NO)^2- ions.