Halogen substitution effects on crystal structures and magnetic properties in nickel dithiolate molecular crystals

A series of nickel dithiolene molecular crystals [Et 3 N(CH 2 ) 3 X][Ni(mnt) 2 ] ( 1 : X = H, 2 : X = Cl, 3 : X = Br and 4 : X = I and Br; mnt 2− = maleonitriledithiolate) were prepared by introducing triethylpropylammonium derivatives (X-CH 2 CH 2 CH 2 -NEt 3 + ) into [Ni(mnt) 2 ] − building blocks. 1 crystallizes in a monoclinic system with the space group P 2 1 / n at 293 K, and the cations and anions in 1 are arranged in columnar segregated stacks along the a -axis direction. Crystals 2 and 3 also belong to monoclinic systems with space groups P 2 1 / n and P 2 1 / c , but 4 crystallizes in a triclinic system with the space group P 1&cmb.macr;. Interactions between [Ni(mnt) 2 ] − ions in all crystals are antiferromagnetic, and the magnitudes of the interactions are qualitatively consistent with the strength of intermolecular interactions estimated from transfer integrals, where interactions between [Ni(mnt) 2 ] − ions are greater than the others in all crystals. The magnetic measurement data demonstrate that antiferromagnetic behavior was observed in 1 and can be fitted well through the 1D alternating linear chain model. Crystal 2 shows spin dimer magnetic behavior, and the magnetic susceptibilities of 3 and 4 show Curie-Weiss-type paramagnetic character in the whole temperature regions. This study showed that halogen substitution on the cations has significant effects on the arrangement and magnetic behavior of [Ni(mnt) 2 ] − . The substitution of halogens on distinct nickel dithiolene molecular crystals [Et 3 N(CH 2 ) 3 X][Ni(mnt) 2 ] has a noteworthy impact on the arrangement and magnetic behavior of [Ni(mnt) 2 ] − .