Pentanuclear Cyanide-Bridged Complexes with High Spin Ground States S=6 and 9: Characterization and Magnetic Properties

Two pentanuclear complexes are obtained from the reaction of hexacyanochromate(III) with one to two molar equivalents of [Ni(H2O)6]2+ and bidentate organic ligands that chelate the metal ion, leaving two coordination sites in cis positions. Even though the crystal structure was not solved, the full characterization supports the formation of pentanuclear discrete species. [Cr(CN)6]2[Ni(HIM2-py)2]3·7H2O, 1, has a ground spin state S=6 owing to the ferromagnetic interaction between CrIII (S= 3/2) and NII (S=1). The presence of six organic radicals that couple ferromagnetically with NiII in [Cr(CN)6]2[Ni(IM2-py)2] 3·7H2O, 2, leads to an S=9 ground state. A.c. susceptibility measurements below 2K indicate the occurrence of an antiferromagnetic order at 1.5 K in 2.