Crystal structures of tetramethylammonium (2,2′-bipyridine)tetracyanidoferrate(III) trihydrate and poly[[(2,2′-bipyridine-κ2N,N′)di-μ2-cyanido-dicyanido(μ-ethylenediamine)(ethylenediamine-κ2N,N′)cadmium(II)iron(II)] monohydrate]

Abstract

The crystal structures of the building block tetramethylammonium (2,2′-bipyridine-κ2N,N′)tetracyanidoferrate(III) trihydrate, [N(CH3)4][Fe(CN)4(C10H8N2)]·3H2O, (I), and a new two-dimensional cyanide-bridged bimetallic coordination polymer, poly[[(2,2′-bipyridine-κ2N,N′)di-μ2-cyanido-dicyanido(μ-ethylenediamine-κ2N:N′)(ethylenediamine-κ2N,N′)cadmium(II)iron(II)] monohydrate], [CdFe(CN)4(C10H8N2)(C2H8N2)2]·H2O, (II), are reported. In the crystal of (I), pairs of [Fe(2,2′-bipy)(CN)4]−units (2,2′-bipy is 2,2′-bipyridine) are linked together through π–π stacking between the pyridyl rings of the 2,2′-bipy ligands to form a graphite-like structure parallel to theabplane. The three independent water molecules are hydrogen-bonded alternately with each other, forming a ladder chain structure withR44(8) andR66(12) graph-set ring motifs, while the disordered [N(CH3)4]+cations lie above and below the water chains, and the packing is stabilized by weak C—H...O hydrogen bonds. The water chains are further linked with adjacent sheets into a three-dimensional networkviaO—H...O hydrogen bonds involving the lattice water molecules and the N atoms of terminal cyanide groups of the [Fe(2,2′-bipy)(CN)4]−building blocks, forming anR44(12) ring motif. Compound (II) features a two-dimensional {[Fe(2,2′-bipy)(CN)4Cd(en)2]}nlayer structure (en is ethylenediamine) extending parallel to (010) and constructed from {[Fe(2,2′-bipy)(CN)4Cd(en)]}nchains interlinked by bridging en ligands at the Cd atoms. Classical O—H...N and N—H...O hydrogen bonds involving the lattice water molecule and N atoms of terminal cyanide groups and the N—H groups of the en ligands are observed within the layers. The layers are further connectedviaπ–π stacking interactions between adjacent pyridine rings of the 2,2′-bipy ligands, completing a three-dimensional supramolecular structure.