Crystal structures of tetramethylammonium (2,2′-bipyridine)tetracyanidoferrate(III) trihydrate and poly[[(2,2′-bipyridine-κ2 N,N′)di-μ2-cyanido-dicyanido(μ-ethylenediamine)(ethylenediamine-κ2 N,N′)cadmium(II)iron(II)] monohydrate]

The crystal structures of the building block tetramethylammonium (2,2′-bipyridine-κ2 N,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-κ2 N,N′)di-μ2-cyanido-dicyanido(μ-ethylenediamine-κ2 N:N′)(ethylenediamine-κ2 N,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 the ab plane. The three independent water molecules are hydrogen-bonded alternately with each other, forming a ladder chain structure with R 4 4(8) and R 6 6(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 network via O - 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 an R 4 4(12) ring motif. Compound (II) features a two-dimensional {[Fe(2,2′-bipy)(CN)4Cd(en)2]} n layer structure (en is ethylenediamine) extending parallel to (010) and constructed from {[Fe(2,2′-bipy)(CN)4Cd(en)]} n chains 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 connected via π-π stacking interactions between adjacent pyridine rings of the 2,2′-bipy ligands, completing a three-dimensional supramolecular structure. © 2016.