Novel molecular staircases constructing from H-bonding interactions based on the building blocks of [Ni(mnt)2]^- ions: syntheses, crystal structures, EPR spectra and magnetic properties

Two new ion-pair compounds, consisting of 1-(4′-R-phenacyl)pyridinium derivatives and bis(maleonitriledithiolato)nickelate, have been synthesized and characterized structurally (R=NMe₂ (1) and H (2)). In crystal 1, H-bonding interactions connecting the cations and anions lead a molecular staircase to form. The adjacent paramagnetic anions are effectively separated by nonmagnetic cations, and the magnetic behavior of 1 is nearly an isolated spin-system, which is supported by the results both EPR (which possesses the very narrow half-width at half-height of ∼18 Gs) and temperature dependence of magnetic susceptibility. While the cations and anions arrange alternately layered structure in crystal 2. In an anionic layer, the neighboring dimers form an anionic chain via peripheral S⋯S stacking interactions. The magnetic feature of 2 denotes the presence of antiferromagnetic interactions between the nearest-neighboring spins, but deviates from any dimer or alternating chain magnetic model.