Odd–Even Effect Observed in [Ni(dmit)<sub>2</sub>] Complex Salts of Quaternary Ammonium Cation with Both Benzyl Groups and ω-Phenylalkyl Groups
作者:Masahiro Saeki、Kotaro Dai、Shuhei Ichimura、Yoshinori Tamaki、Kazuaki Tomono、Kazuo Miyamura
DOI:10.1246/bcsj.20140309
日期:2015.2.15
A series of [Ni(dmit)2] (dmit: 1,3-dithiole-2-thione-4,5-dithiolate) complex salts of benzyldimethyl(ω-phenylalkyl)ammonium cation (BnCnPh: n represents the alkylene chain length; n = 1–4) have been prepared and characterized by X-ray crystallographic structural analysis. All complex salts were found to be composed of alternant stacks of layers of [Ni(dmit)2] anion dimers and cations (Layer I), and isolated cation layers (Layer II). In BnC3Ph complex salt, polymorphs, P1 (α-form) and P2(1)/c (β-form) crystals are obtained from similar crystallizing conditions. One of the biggest structural differences is the arrangement of [Ni(dmit)2] anion dimers; herringbone in α-form, while nearly parallel in β-form. Other BnCnPh complex salts adopt herringbone structure. Interestingly, BnCnPh series (n = 1, 2, 3α, 4) exhibit three types of pronounced odd–even effect in the crystal structures; 1. Dihedral angles between the two kinds of terminal phenyl groups, 2. Angles between [Ni(dmit)2] anion dimers, and 3. Ni–N+ distances. Such a structural feature is a consequence of the bulkiness of cation involving two phenyl groups. Introduction of terminal phenyl group is concluded to have increased the steric effect and led to the formation of the novel crystal structure of [Ni(dmit)2] complex salts.
一系列苄基二甲基(ω-苯基烷基)铵阳离子的[Ni(dmit)2](dmit:1,3-二硫醇-2-硫酮-4,5-二硫醇)络盐(BnCnPh:n代表亚烷基链长; n = 1–4) 已被制备并通过 X 射线晶体结构分析进行表征。发现所有复合盐均由[Ni(dmit)2]阴离子二聚体和阳离子层(层I)和孤立的阳离子层(层II)的交替堆叠组成。在 BnC3Ph 复合盐、多晶型物、P1(α 型)和 P2(1)/c(β 型)晶体中,从类似的结晶条件获得。最大的结构差异之一是[Ni(dmit)2]阴离子二聚体的排列; α 型呈人字形,β 型则近乎平行。其他BnCnPh复合盐采用人字形结构。有趣的是,BnCnPh系列(n=1、2、3α、4)在晶体结构中表现出三种明显的奇偶效应; 1. 两种末端苯基之间的二面角,2. [Ni(dmit)2] 阴离子二聚体之间的角度,以及 3. Ni-N+ 距离。这种结构特征是涉及两个苯基的阳离子体积庞大的结果。结论是末端苯基的引入增加了空间效应并导致[Ni(dmit)2]络盐的新型晶体结构的形成。