Two quasi-one-dimensional molecular solids based on Ni(mnt)2 anion: Crystal structures, spectra, and magnetic properties

Article abstract of DOI:10.1016/j.ica.2005.12.050

Two new molecular solids, [DiClBzPyNH₂][Ni(mnt)₂] (1) and [DiClBzPyN(CH₃)₂][Ni(mnt)₂] (2) ([DiClBzPyNH₂]⁺ = 1-(2′,4′-dichlorobenzyl)-4- aminopyridinium, [DiClBzPyN(CH₃)₂]⁺ = 1-(2′,4′-dichlorobenzyl)-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 magnetic chain within a Ni(mnt)2- column through Ni?S, S?S, Ni?Ni, or π?π interactions. The chain is alternating in 1 with Ni?Ni distances of 3.869 and 4.074 A?, while it is uniform in 2 with Ni?Ni distances of 4.159 A?. Magnetic susceptibility measurements in the temperature range 1.8-300 K show that 1 exhibits antiferromagnetic behavior, while 2 shows an unusual magnetic phase transition around 140 K, and antiferromagnetic interaction in the high-temperature (HT) phase and spin gap in the low-temperature (LT) phase. The phase transition for 2 is second order by determination of DSC analyses.