Cu–Ni heterobimetallic compounds. Part 2: Study of the system Cu(II)–bpy–[Ni(CN)4]2− (bpy = 2,2′-bipyridine)

Two new complexes [Ni(bpy)3][Cu(CN)3]·4.5H2O (1) and [Cu(bpy)2(CN)]2[Ni(CN)4]·4H2O (2) (bpy = 2,2′-bipyridine) have been synthesized from aqueous-ethanolic solution. The crystal structures of both 1 and 2 are ionic. The crystal structure of 1 is built up of [Ni(bpy)3]2+ and [Cu(CN)3]2− complex ions, and disordered solvated water molecules. While the Ni(II) atom is octahedrally coordinated by three chelate bonded bidentate bpy ligands with Ni–N bond 2.0851(1) Å (6×), the Cu(I) atom is in trigonal coordination with Cu–C bond 1.9440(1) Å (3×). Crystal structure of 2 consists of a rare [Cu(bpy)2(CN)]+ complex cations, [Ni(CN)4]2− complex anions (ratio 2:1) and solvated water molecules; in the complex cation the Cu(II) atom is penta-coordinated with terminal cyanido ligand. In both crystal structures the not coordinated water molecules are involved in hydrogen bonding. Thermal study on air of both 1 and 2 did not indicate formation of a stable intermediate; the solid residues are formed of a mixture of CuO and NiO. Magnetic susceptibilities of both 1 and 2 are described by Curie–Weiss behavior with θ values of −1.37 K (1) and −0.54 K (2) due to the action of weak antiferromagnetic interactions in 1 and 2, respectively.

From aqueous-ethanolic systems Cu2+–bpy–[Ni(CN)4]2− two novel Cu–Ni heterobimetallic complexes [Ni(bpy)3][Cu(CN)3]·4.5H2O (1) and [Cu(bpy)2(CN)]2[Ni(CN)4]·4H2O (2) were isolated. Both crystal structures are ionic and in 2 a rare [Cu(bpy)2(CN)]+ cation is present. Magnetic properties of both complexes in the low temperature region (<10 K) are governed by weak antiferromagnetic interactions.Figure optionsDownload as PowerPoint slide