The self-assembly reaction of [Cr(CN) 6 ] 3-, Ln 3+ , and a chelated phen ligand resulted in the first examples of cyanobridged 3d-4f helical chains [Ln(phen) 3 (H 2 O)][Cr(CN) 6 ]· 3H 2 O [Ln = La (1), Ce (2), Pr (3) and Nd (4)], in which the [a]

Self-assembly reaction between hydrated rare-earth (RE) nitrates RE(NO 3 ) 3 ·6H 2 O with K 3 Fe(CN) 6 in H 2 O/DMF solution by employing the tridentate ligand 2,2Ј:6Ј,2ЈЈ-terpyridine (terpy) as a capping ligand has yielded three cyanide-bridged compounds [RE(terpy)(DMF)(H 2 O) 2 ][Fe(CN) 6 ]·6H 2 O [RE = Y (1), Tb (2), Dy (3)]. FT-IR spectra confirmed the presence of terpy ligands and cyanide groups in compounds 1-3. Single-crystal X-ray structural analysis

The structure of the title compound, (C16H17N2)3[Co(CN)6]·5H2O, consists of three 3,4,7,8-tetra­methyl-1,10-phenanthrolin-1-ium cations, a [Co(CN)6]3− anion and five water mol­ecules of crystallization, one of which is disordered over two sets of sites in a 0.587 (15):0.413 (15) ratio. The [Co(CN)6]3− anion exhibits an octa­hedral geometry. In the structure, cations and anions are linked alternatively through O—H⋯O, O—H⋯N, N—H⋯O and N—H⋯N hydrogen bonds, π–π inter­actions [centroid–centroid distances = 3.523 (2)–4.099 (2) Å] and van der Waals forces, forming a three-dimensional supra­molecular network.

In the structure of the title complex, {[CeFe(CN)6(H2O)2]·2H2O}n, the CeIII and FeIII atoms exhibit square anti­prismatic [CeN6(H2O)2] (site symmetry m2m) and octahedral [FeC6] (site symmetry 2/m) coordination geometries, respectively. The metal atoms are linked alternately through the cyanide groups, forming a three-dimensional framework in which the {Ce2Fe2(CN)4} puckered square unit is the basic building block. The crystal packing is enforced by O—H⋯O and O—H⋯N hydrogen bonds, including the uncoordinated water molecule which is located on a mirror plane.

The asymmetric unit of the title complex, (C12H9N2)3[Fe(CN)6]·C2H5OH·3H2O, consists of two half [Fe(CN)6]3− anions located on inversion centers, three 1,10-phenanthrolin-1-ium cations, [Hphen]+, an ethanol and three water solvent mol­ecules. The average Fe—C and C—N bond lengths are 1.942 (6) and 1.154 (3) Å, respectively, while the Fe—C—N angles deviate slightly from linearity with values ranging from 177.8 (2) to 179.7 (2)°. The FeIII atoms adopt a distorted octa­hedral geometry. All the species are linked through O—H⋯N, N—H⋯O and O—H⋯O hydrogen-bonding inter­actions, resulting in a three-dimensional supra­molecular network.