Magnetic characteristics of bimetallic assemblies, [Ni(en)2]3[M(CN)6]2· 2H2O (en = H2NCH2CH2NH2 ; M = Fe, Mn, Cr or Co), with a one-dimensional rope-ladder chain structure

Abstract

Four bimetallic assemblies, [Ni(en) ₂ ] ₃ [M(CN) ₆ ] ₂ · 2H ₂ O (en = H ₂ NCH ₂ CH ₂ NH ₂ ; M = Fe 1, Mn 2, Cr 3 or Co 4), have been prepared in crystalline form and their magnetic properties studied. A crystal structure analysis of complex 4 revealed a one-dimensional rope-ladder chain structure extended through Co–CN–Ni–NC–Co linkages. Compounds 1–3 show ferromagnetic intramolecular interaction based on the strict orthogonality of magnetic orbitals between adjacent nickel(II) and metal(III) ions. All the compounds show antiferromagnetic intermolecular interaction and hence no magnetic ordering. A polycrystalline sample of 1 was metamagnetic below 18.6 K. This is interpreted in terms of a disorder of the network containing pseudo-two- and -three-dimensional domains.