Odd–Even Effect and Unusual Behavior of Dodecyl-Substituted Analogue Observed in the Crystal Structure of Alkyltrimethylammonium–[Ni(dmit)<sub>2</sub>]<sup>−</sup>Salts
作者:Kotaro Dai、Kuniharu Nomoto、Shinji Ueno、Kazuaki Tomono、Kazuo Miyamura
DOI:10.1246/bcsj.20100306
日期:2011.3.15
A series of [Ni(dmit)2]− (dmit: 1,3-dithiole-2-thione-4,5-dithiolato) salts of alkyltrimethylammonium (Cn: n represents the alkyl chain length; n = 3 and 5–18) have been prepared and analyzed by X-ray structural analysis. All complex salts have been found to be composed of alternate sheets of [Ni(dmit)2]− anions and sheets of cations with a pronounced interdigitation of the alkyl chains. However, molecular arrangement differed between (C3)[Ni(dmit)2] and other (Cn)[Ni(dmit)2] (n = 5–18). Adjacent cations were aligned along the long axis of [Ni(dmit)2]− anion in C3 complex salt, while in others (C5–C18 complex salts), they were aligned toward the short axis. Such a difference in arrangement arose from correlativity between the lengths of the long axis of cation and anion, namely CLCA. Furthermore, relative orientation between the alkyl chain of cation and [Ni(dmit)2]− anion differed between the odd- and even-numbered cations for C10–C18. Whereas the plane of alkyl chain for odd-numbered cation was normal to the plane of [Ni(dmit)2]− anion, that of even-numbered cation was parallel. It was also found that C12 analog behaved like odd-numbered cations. However, in C12 salt, the end methyl group of the dodecyl group adopted unusual end-gauche conformation.
一系列[Ni(dmit)2]−(dmit:1,3-二硫杂环戊烯-2-硫酮-4,5-二硫醇)的烷基三甲基铵盐(Cn:n代表烷基链长度;n = 3和5–18)已被制备并通过X射线结构分析进行了研究。所有复合盐均被发现由交替的[Ni(dmit)2]−阴离子层和阳离子层组成,阳离子层的烷基链存在显著的互插结构。然而,分子排列在(C3)[Ni(dmit)2]和其他(Cn)[Ni(dmit)2](n = 5–18)之间有所不同。在C3复合盐中,相邻的阳离子沿[Ni(dmit)2]−阴离子的长轴排列,而在其他(C5–C18复合盐)中,它们朝向短轴排列。这种排列差异源于阳离子和阴离子长轴长度的相关性,即CLCA。此外,对于C10–C18,阳离子烷基链与[Ni(dmit)2]−阴离子之间的相对取向在奇数和偶数编号阳离子之间有所不同。奇数编号阳离子的烷基链平面垂直于[Ni(dmit)2]−阴离子平面,而偶数编号阳离子的烷基链平面则平行。还发现C12类似物表现得像奇数编号阳离子。然而,在C12盐中,十二烷基的末端甲基采取了不寻常的末端-旁式构象。