Syntheses, structures, and magnetic properties of two new molecular magnets containing Ni(mnt) 2 monoanion and substituted 4-dimethylaminopyridinium

Abstract

Two new molecular magnets, [BzPyN(CH 3) 2][Ni(mnt) 2] ( 1) and [NO 2BzPyN(CH 3) 2][Ni(mnt) 2] ( 2)([BzPyN(CH 3) 2] + = 1-benzyl-4-dimethylaminopyridinium, [NO 2BzPyN(CH 3) 2] + = 1-(4′-nitrobenzyl)-4-dimethylaminopyridinium, and mnt 2− = maleonitriledithiolate) have been prepared and characterized by elemental analyses, IR, MS spectra, single crystal X-ray diffraction and magnetic susceptibility. The Ni(III) ions of both 1 and 2 form a 1D zigzag alternating magnetic chain within a Ni ( mnt ) 2 - column through Ni⋯S, Ni⋯Ni, Ni⋯N, S⋯S, or π⋯π interactions. Magnetic susceptibility measurements in the temperature range 1.8–300 K show that 1 exhibits antiferromagnetic behavior, while 2 shows a spin gap transition around 170 K, and antiferromagnetic interaction in the high-temperature phase (HT) and spin gap in the low-temperature phase (LT). The phase transition for 2 is second-order by determination of DSC analyses.