title: Observation of metal ion dependent packing structures and magnetic behaviors of metal-bis-1, 2-dithiolene complexes.
abstract: The crystal structures and magnetic properties were investigated experimentally and theoretically for two S = ½ spin chain complexes, which consist of [M(mnt)(2)](-) (M = Pt for 1 or Pd for 2) with 1-(4'-bromo-2'-flurobenzyl)-4-aminopyridinium (1-BrFBz-4-NH(2)Py(+)). The 1-BrFBz-4-NH(2)Py(+) cations exhibit different molecular conformations and arrangements in 1 and 2; the [M(mnt)(2)](-) anions form regular stacks in 1, whereas they form irregular stacks in 2. In addition, the intermolecular interactions between the [M(mnt)(2)](-) anions and cations are also different from each other in the crystals of 1 and 2. Complex 1 shows the magnetic characteristics of a low-dimensional antiferromagnetic coupling spin system with a spin-Peierls-type transition around 7 K, and complex 2 exhibits diamagnetism over the temperature range of 5-300 K. Theoretical analyses, based on the calculations for the charge density distributions of [Pt(mnt)(2)](-) and [Pd(mnt)(2)](-) anions and the magnetic exchange constants within the anion spin chains, addressed the diverse molecular alignments in the crystals of 1 and 2 and distinct magnetic behaviors between 1 and 2.
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering and College of Science, Nanjing University of Technology, Nanjing, P R China.
authors.forename: Wen-Bo
authors.initials: WB
authors.lastname: Pei
authors.forename: Jian-Sheng
authors.initials: JS
authors.lastname: Wu
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Ren
authors.forename: Zheng-Fang
authors.initials: ZF
authors.lastname: Tian
authors.forename: Jingli
authors.initials: J
authors.lastname: Xie