Lanthanide-ion-tuned magnetic properties in a series of three-dimensional cyano-bridged LnIIIWV assemblies

Abstract

The reaction of [W(CN)₈]³⁻ with Ln³⁺ and pyrazine in acetonitrile yielded a series of isostructural compounds formulated as Ln(H₂O)₄(pyrazine)_0.5W(CN)₈ (Ln = La(1), Ce(2), Pr(3), Nd(4), Sm(5), Eu(6), Gd(7)). The Ln(III) and W(V) centers in the structure are linked through cyanide groups to form two-dimensional (2D) layers, which are further pillared by pyrazine, generating 3D frameworks. The magnetic behavior for compounds 1–7 were driven by the lanthanide ions involved. The Ln(III) and W(V) ions in compounds 2 and 5 are ferromagnetically coupled with magnetic ordering occurring at 2.8 K, comparable with magnetic ordering with the critical temperature of 1.9 K for compound 4. In addition, the antiferromagnetic interactions were observed in compounds 3 and 7, while no significant magnetic couplings were found in compounds 1 and 6.