Low-dimensional compounds containing cyanide groups. XXV. Synthesis, spectroscopic properties and crystal structures of two ionic iron(II) complexes with tricyanomethanide: tris(1,10-phenanthroline-κ2 N,N′)iron(II) bis(tricyanomethanide) and tris(2,2′-bipyridine-κ2 N,N′)iron(II) bis(tricyanomethanide) sesquihydrate

Abstract

Two new diamagnetic coordination compounds, [Fe(phen)3][C(CN)3]2, (I), and [Fe(bpy)3][C(CN)3]2·1.5H2O, (II), have been synthesized and characterized by single-crystal X-ray diffraction analysis, and IR and UV–Vis spectroscopy (phen is 1,10-phenanthroline, C12H8N2, and bpy is 2,2′-bipyridine, C10H8N2). Both compounds are ionic with distorted octahedral [Fe(phen)3]2+ or [Fe(bpy)3]2+ complex cations, with average Fe—N distances of 1.977 (2) and 1.971 (3) Å, respectively, and two uncoordinated planar tricyanomethanide, or [C(CN)3]−, counter-anions balancing the positive charges of the cations. Solvent water molecules and tcm anions in (II) are linked via O—H...N hydrogen bonds into negatively charged layers and the interlayer space is filled by [Fe(bpy)3]2+ cations. The structures of (I) and (II) are stabilized by π–π interactions between the stacked aromatic rings of the phen ligands of two adjacent cations and by O—H...N hydrogen bonds, respectively, and also by π–π stacking interactions between phen and tcm units in (I).