Synthesis, crystal structure and magnetic properties of a novel one-dimensional nickel(III) chain complex showing ferromagnetic ordering at low temperature

A novel ferromagnetic complex [BrFBzPy][Ni(mnt)₂], where [BrFBzPy]⁺ = 1-(4′-bromo-2′-fluorobenzyl)pyridinium and mnt^2- = maleonitriledithiolate, has been prepared and characterized. In the crystal structure the most prominent feature is that the [Ni(mnt)₂]^- anions and [BrFBzPy]⁺ cations form a well-separated stacking column along the c-axis, within which the [Ni(mnt)₂]^- anions are uniformly spaced to give a one-dimensional (1-D) chain structure. The magnetic properties of this complex have been investigated in the temperature range 1.8-300 K and its magnetization studies show there exists ferromagnetically coupled interactions within the [Ni(mnt)₂]^- anion chain (J = 42.2 cm^-1), and antiferromagnetically coupled interactions between [Ni(mnt)₂]^- anion chains (J_eff = -4.78cm^-1). The temperature dependences of the ac susceptibility revealed that this 1-D chain system is ferromagnetically ordered around 2 K and X_ac measurements performed at different magnetic fields and frequencies suggest that there may coexist a degree of spin glass behaviour at low temperature.