One-dimensional structure ofcatena-poly[tetraethylammonium [tetracyanoiron(III)-μ-cyano-[bis(ethylenediamine)cadmium(II)]-μ-cyano] tetrahydrate

Abstract

The title compound, {(C8H20N)[CdFe(CN)6(C2H8N2)2]·4H2O}n, was isolated from the aqueous system Cd2+/ethyl­ene­diamine (en)/[Fe(CN)6]3− in the presence of [Et4N]Br. The crystal structure is dominated by a one-dimensional motif, viz. a negatively charged 2,2-CT (cis–trans) [–Cd(en)2—NC—Fe(CN)4—CN–]nn− chain. The Cd and Fe atoms of the anion and the N atom of the cation all lie on twofold axes. The ethyl groups of the cation are equally disordered over two orientations. The cationic building block of the chain consists of a CdII atom coordinated by two chelating en ligands, and the distorted octa­hedral coordination is completed by two bridging cyano ligands in cis positions. The anionic building block is an [Fe(CN)6]3− anion in which the FeIII atom is octa­hedrally coordinated by six cyano ligands; two of the cyano ligands, in trans positions, are bridging. The uncoordinated water mol­ecules link neighbouring chains through O—H⋯N and N—H⋯O hydrogen bonds.