Pullen Anthony E., Faulmann Christophe, Pokhodnya Konstantin I., Cassoux Patrick, Tokumoto Madoka
Equipe Précurseurs Moléculaires et Matériaux, LCC-CNRS, 205 Route de Narbonne, 31077 Toulouse Cédex, France, and Electrotechnical Laboratory, 1-1-4 Umezono, Tsukuba, Ibaraki 305, Japan.
Inorg Chem. 1998 Dec 28;37(26):6714-6720. doi: 10.1021/ic980876v.
A series of metal bis-mnt complexes (mnt = 1,2-dithiolatomaleonitrile) with the trimethylammonium methylferrocene cation have been synthesized and characterized using X-ray diffraction, magnetic susceptibility, and differential scanning calorimetry measurements. The complexes have the formulas (FcCH(2)NMe(3))[Ni(mnt)(2)] (2), (FcCH(2)NMe(3))[Pt(mnt)(2)] (3), and (FcCH(2)NMe(3))(2)[Cu(mnt)(2)] (4) (where Fc = ferrocene). At 300 K, the crystal structures of 1:1 complexes 2 and 3 are very similar. They consist of pairs of M(mnt)(2) in a slipped configuration packed in stacks. Each M(mnt)(2) stack is separated from adjacent stacks by two columns of cations. Within the pairs, the M(mnt)(2) anions interact via short M.S contacts, while there are no short contacts between the pairs. Complex 4, which has a 2:1 stoichiometry, exhibits a markedly different packing arrangement of the anionic units. Due to the special position of the Cu atom in the asymmetric unit cell, Cu(mnt)(2)(-) dianions are completely isolated from each other. The magnetic susceptibility behavior of the nickel complex is consistent with the presence of magnetically isolated, antiferromagnetically (AF) coupled Ni(mnt)(2) pairs with the AF exchange parameter, J = -840 cm(-)(1). The platinum complex undergoes an endothermic structural phase transition (T(p)) at 247 K. Below T(p) its structure is characterized by the formation of magnetically isolated Pt(mnt)(2)(2)(-) dimers in an eclipsed configuration with short Pt.Pt and S.S contacts between monomers. In the magnetic properties, the structural changes reveal themselves as an abrupt susceptibility drop implying a substantial increase of the AF exchange parameter. A mechanism of the phase transition in the platinum compound is proposed. For compound 4, paramagnetic behavior is observed.
一系列含有三甲基铵甲基二茂铁阳离子的金属双 - mnt配合物（mnt = 1,2 - 二硫代原子马来腈）已被合成，并通过X射线衍射、磁化率和差示扫描量热法测量进行了表征。这些配合物的化学式为(FcCH₂NMe₃)[Ni(mnt)₂] (2)、(FcCH₂NMe₃)[Pt(mnt)₂] (3) 和 (FcCH₂NMe₃)₂[Cu(mnt)₂] (4)（其中Fc = 二茂铁）。在300 K时，1:1配合物2和3的晶体结构非常相似。它们由成对的呈滑移构型的[M(mnt)₂]⁻堆积成层组成。每个[M(mnt)₂]⁻层与相邻层被两列阳离子隔开。在这些对中，[M(mnt)₂]⁻阴离子通过短的M - S接触相互作用，而这些对之间没有短接触。化学计量比为2:1的配合物4表现出阴离子单元明显不同的堆积排列。由于Cu原子在不对称晶胞中的特殊位置，[Cu(mnt)₂]²⁻二阴离子彼此完全隔离。镍配合物的磁化率行为与存在磁隔离的、反铁磁（AF）耦合的[Ni(mnt)₂]⁻对一致，反铁磁交换参数J = - 840 cm⁻¹。铂配合物在247 K发生吸热结构相变（Tp）。在Tp以下，其结构的特征是形成磁隔离的[Pt(mnt)₂]²²⁻二聚体，呈重叠构型，单体之间有短的Pt - Pt和S - S接触。在磁性方面，结构变化表现为磁化率突然下降，表示反铁磁交换参数大幅增加。提出了铂化合物相变的一种机制。对于化合物4，观察到顺磁行为。
