Hexacyanocobaltate(III) anions as precursors of Co(II)-Ni(II) cyano-bridged multidimensional assemblies: hydrothermal syntheses, crystal and powder X-ray structures, and magnetic properties

Three novel cyanide-bridged heterobimetallic coordination polymers have been synthesized by hydrothermal routes, in superheated water solutions, by using K3Co(CN)6], NiCl2.6H2O, and alpha-diimine ligands: Ni(CN)4Co(phen)] (1; phen = 1,10-phenanthroline), Ni(CN)4Co(2,2'-bipy)] (2; 2,2'-bipy = 2,2'-bipyiridine), and Ni(CN)4Co(2,2'-bipy)2] (3). The isostructural compounds 1 and 2 contain a two-dimensional network with Co(II) centers octahedrally coordinated by one chelating 2,2'-bipy ligand and four cyanide groups of four distinct Ni(CN)4]2-, through crystallographically equivalent, bridging units. Compound 3 contains one-dimensional zigzag chains in which the Co(II) ion is coordinated by two chelating 2,2'-bipy ligands and two cyanides from two different Ni(CN)4]2- units cis to each other. These compounds have been fully characterized by single-crystal or unconventional powder X-ray diffraction analyses and variable-temperature magnetic measurements.