A new quasi-one-dimensional molecular solid based on Ni(mnt)2 anion: Crystal structure and spin–gap transition

A new molecular solid, [1-(4′-bromo-2′-fluorobenzyl)-4-dimetylaminopyridinium]-bis(maleonitriledithiolato)nickel(III), (BrFBzPyN(CH3)2(Ni(mnt)2)(1), has been prepared and characterized by elemental analyses, IR, ESI-MS spectra, single crystal X-ray diffraction and magnetic measurements. Compound 1 crystallizes in the orthorhombic space group Pnma, a=20.579(4) Å, b=7.078(1) Å, c=17.942(4) Å, α=β=γ=90°, V=2613.3(9) Å3, Z=4. The Ni(III) ions of 1 form a quasi-one-dimensional Zigzag magnetic chain within a Ni(mnt)2− column through Ni⋯S, S⋯S, Ni⋯Ni, or π⋯π interactions with an Ni⋯Ni distance of 4.227 Å. Magnetic susceptibility measurements in the temperature range 2–300 K show that 1 exhibits a spin–gap transition around 200 K, and antiferromagnetic interaction in the high-temperature phase (HT) and spin gap in the low-temperature phase (LT). The transition for 1 is second-order phase transition as determined by DSC analyses.