Molecular Spin Ladders Constructed from [Ni(dmit)2]− Building Blocks: Synthesis, Structure and Physical Properties

Abstract

A new ion-pair complex [1-(4-bromobenzyl)-3-methylpyridinium][Ni(dmit)2] (1), in which dmit = 4,5-dimercapto-1,3-dithiole-2-thione, has been synthesized and structurally characterized. The anions of [Ni(dmit)2]− stack into dimers, which further construct into a two-leg ladder through lateral S···S interactions. The weak H-bonding interactions of C–H···S and van de Waals interactions between anion and cations were observed. The magnetic susceptibilities measured from 2–300 K indicate an AFM exchange interaction domination and an AFM ordering below ~8 K. The best fit to magnetic susceptibility above 40 K, using a dimer model with s = ½, gives rise to Δ/kB = 29.8 K, zJ′ = −0.72 K, C = 3.40 × 10−3 emu K mol−1 and χ 0 = −5.8 × 10−6 emu mol−1 with a fixed g = 2.0. Cyclovoltammetry revealed two quasi-reversible one-electron steps, which are attributed to Ni(IV/III) and Ni(III/II) redox couples. [A novel complex [1-(4-bromobenzyl)-3-methylpyridinium][Ni(dmit)2] has been synthesized and structurally characterized. The anions of [Ni(dmit)2]− stack into dimers, which further construct into two-leg ladder through lateral S···S interactions. The weak H–bonding interactions of C–H···S and van de Waals interactions between anion and cations were observed. Moreover, its magnetic property and electrochemical property have been investigated] .