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

Abstract

Two new complexes [Ni( bpy) 3][Cu(CN) 3]·4.5H 2O ( 1) and [Cu( bpy) 2(CN)] 2[Ni(CN) 4]·4H 2O (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.