Synthesis, crystal structures and magnetic properties of two new hetero-bimetallic assemblies

Two new cyanide-bridged 3d-4f hetero-dinuclear complexes, namely Ln(DMF)₄(H₂O)₃(μ-CN)Co(CN)₅ · H₂O (Ln=Nd (1) and Gd (2), DMF=N,N-dimethylformamide), were synthesized by the facile reaction of LnCl₃.6H₂O and K₃Co(CN)₆. Characterization includes microanalysis, IR spectrometric identifications, X-ray crystallographic analysis and magnetic properties. Both 1 and 2 crystallize in the centrosymmetric monoclinic space group P2₁/n (No. 14) with Z=4. The lanthanide(III) ions are eight-coordinate in a square-antiprism arrangement, while cobalt(III) ions are six-coordinate in an octahedral environment in each complex. A cyanide bridge links an LN(III) ion to a Co(III) ion. Molecules in the crystal cell of each compound are held together by van der Waals forces and a network of hydrogen bonding. Magnetic analysis shows that antiferromagnetic interactions are observed below 7 K for both 1 and 2, which are attributed to intermolecular interactions between the Ln(III) ions in the network through hydrogen bonds. This series of compounds may be of importance in photo-induced magnetism because of the cyanide bridge between 3d and 4f metals.