二维层状自旋交叉配合物[FeIIH3L(Me)][FeIIL(Me)]X（X-=ClO4-、BF4-、PF6-、AsF6-和SbF6-；H3L(Me)=三[2-(((2-甲基咪唑-4-基)亚甲基)氨基)乙基]胺）的层间相互作用

Interlayer interaction of two-dimensional layered spin crossover complexes [FeIIH3L(Me)][FeIIL(Me)]X (X-=ClO4-, BF4-, PF6-, AsF6-, and SbF6-; H3L(Me)=tris[2-(((2-methylimidazol-4-yl)methylidene)amino)ethyl]amine).

作者信息

Yamada Masahiro, Ooidemizu Makoto, Ikuta Yuichi, Osa Shutaro, Matsumoto Naohide, Iijima Seiichiro, Kojima Masaaki, Dahan Françoise, Tuchagues Jean-Pierre

机构信息

Department of Chemistry, Faculty of Science, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555, Japan.

出版信息

Inorg Chem. 2003 Dec 15;42(25):8406-16. doi: 10.1021/ic034439e.

DOI:10.1021/ic034439e

PMID:14658894

Abstract

A series of two-dimensional (2D) spin crossover complexes, [FeIIH3L(Me)][FeIIL(Me)]X (X-=ClO4-, BF4-, PF6-, AsF6-, SbF6-) 1-5, have been synthesized, where H3L(Me) denotes an hexadentate N6 tripodlike ligand containing three imidazole groups, tris[2-(((2-methylimidazol-4-yl)methylidene)amino)ethyl]amine. Compounds 1-5 exhibit a two-step (HS-FeIIH3L(Me) + HS-[FeIIL(Me)]-) <--> (HS-FeIIH3L(Me) + LS-[FeIIL(Me)]-) <--> (LS-FeIIH3L(Me) + LS-[FeIIL(Me)]-) spin-transition. The crystal structure of [FeIIH3L(Me)][FeIIL(Me)]PF6 (3) was determined at 295, 200, and 100 K. The structure consists of homochiral extended 2D puckered sheets, in which the complementary FeIIH3L(Me) and [FeIIL(Me)]- capped tripodlike components, linked together by imidazole-imidazolate hydrogen bonds, are alternately arrayed in an up-and-down mode. The Fe-N bond distances and angles revealed that the FeII sites of both constituting units are in the high-spin (HS) state at 295 K; at 200 K, the FeII sites of FeIIH3L(Me) and [FeIIL(Me)]- are in the HS and low-spin (LS) states, respectively. The FeII sites of both constituting units are in the LS state at 100 K. The size of the counteranion affects significantly the intra- and interlayer interactions leading to modifications of the spin crossover behavior. The onset of the second spin-transition of the ClO4- (1) and BF4- (2) salts adjoins the first spin-transition, while a mixed (HS-FeIIH3L(Me) + LS-[FeIIL(Me)]-) spin-state spans a temperature range as wide as 70 K for salts 3-5 with larger counteranions, PF6-, AsF6-, and SbF6-, respectively. Compounds 1 and 2 showed remarkable LIESST (light induced excited spin state trapping) and reverse-LIESST effects, whereas 3-5 showed no remarkable LIESST effect. The interlayer interaction due to the size of the counteranion is an important factor governing the spin crossover behavior and LIESST effect.

摘要

合成了一系列二维（2D）自旋交叉配合物[FeIIH3L(Me)][FeIIL(Me)]X（X- = ClO4-、BF4-、PF6-、AsF6-、SbF6-）1-5，其中H3L(Me)表示一种含三个咪唑基团的六齿N6三脚架状配体，即三[2-(((2-甲基咪唑-4-基)亚甲基)氨基)乙基]胺。化合物1-5表现出两步自旋转变：（HS-FeIIH3L(Me) + HS-[FeIIL(Me)]-）<-->（HS-FeIIH3L(Me) + LS-[FeIIL(Me)]-）<-->（LS-FeIIH3L(Me) + LS-[FeIIL(Me)]-）。测定了[FeIIH3L(Me)][FeIIL(Me)]PF6（3）在295 K、200 K和100 K时的晶体结构。该结构由同手性的二维褶皱片组成，其中互补的FeIIH3L(Me)和[FeIIL(Me)]-封端的三脚架状组分通过咪唑-咪唑盐氢键连接在一起，以上下模式交替排列。Fe-N键长和键角表明，两个组成单元的FeII位点在295 K时处于高自旋（HS）状态；在200 K时，FeIIH3L(Me)和[FeIIL(Me)]-的FeII位点分别处于HS和低自旋（LS）状态。在100 K时，两个组成单元的FeII位点均处于LS状态。抗衡阴离子的大小显著影响层内和层间相互作用，导致自旋交叉行为发生改变。ClO4-（1）和BF4-（2）盐的第二次自旋转变起始点与第一次自旋转变相邻，而对于分别含有较大抗衡阴离子PF6-、AsF6-和SbF6-的盐3-5，混合（HS-FeIIH3L(Me) + LS-[FeIIL(Me)]-）自旋态跨越的温度范围高达70 K。化合物1和2表现出显著的光诱导激发自旋态捕获（LIESST）和反向LIESST效应，而3-5则没有显著的LIESST效应。抗衡阴离子大小引起的层间相互作用是控制自旋交叉行为和LIESST效应的重要因素。