Molecule-based magnetic materials based on dinuclear ruthenium carboxylate and octacyanotungstate

Abstract

Two structurally different polymeric complexes consisting of ruthenium(II,III) pivalate ([Ru₂(piv)]₄⁺) (Hpiv = pivalic acid) and octacyanotungstate(V) ([W(CN)₈]³⁻) ions, [{Ru₂(piv)₄}₃W(CN)₈(H₂O)] (1) and (PPh₄)₂[Ru₂(piv)₄W(CN)₈]·0.5H₂O (2), were synthesized. The infrared spectra as well as diffused reflectance spectra confirmed the existence of the ruthenium(II,III) pivalate dimer in 1 and 2. The X-ray crystal structure analysis of 2 showed an alternating arrangement of [Ru₂(piv)]₄⁺ and [W(CN)₈]³⁻ ions in a one-dimensional chain. The temperature-dependent magnetic susceptibility of 2 showed a ferrimagnetic-like behavior. However, the field dependent magnetization curve at 2 K indicates that this complex has an S = 0 ground state. The X-ray crystal structure analysis of 1 showed a two-dimensional layered structure made up of windmill-shaped 28 membered-rings of alternating arrangement of [Ru₂(piv)]₄⁺ and [W(CN)₈]³⁻. The magnetic susceptibility and zero-field-cooled and field-cooled magnetization data of 1 showed that this complex is ferrimagnetic with T_c = 44 K. The field dependence of magnetization exhibited a hysteresis with a coercive field of 5600 Oe at 5 K.