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 K3[Co(CN)6], NiCl2·6H 2O, and α-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.