Antiferromagnetic ordering of the FeBr4− d-spins via strong π–d interaction in a semiconducting EDT-CP-TTFVS·FeBr4 salt
Antiferromagnetic ordering of the FeBr4− d-spins via strong π–d interaction in a semiconducting EDT-CP-TTFVS·FeBr4 salt
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DOI：
10.1039/b900644c
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发表时间：
2009-06
影响因子：
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通讯作者：
X. Shao;Yuhta Yamaji;T. Sugimoto
中科院分区：
文献类型：
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作者：
X. Shao;Yuhta Yamaji;T. Sugimoto
第一：弯曲的供体分子亚乙基二氧（-亚乙基二硫代-）三亚甲基-四硫富瓦烯硫代醌-1，3-二硫代戊烯甲基化物[EDO-CP-TTFVS（1）和EDT-CP-TTFVS（2）]与FeX 4 −（X = Cl，Br）离子形成的1·FeX 4和2·FeX 4阳离子自由基盐以黑色片状单晶的形式获得。其中1·FeCl 4、2·FeCl 4和2·FeBr 4是在Bu 4 N·FeX 4（X = Cl，Br）存在下通过电化学氧化1和2得到的，而1·FeBr 4是通过FeBr 3化学氧化1得到的。所有这些盐都表现出半导体特性。2·FeX 4盐在室温下具有约0.1 S cm-1的相对良好的电导率，其比1·FeX 4的电导率高约100倍。这四种盐的晶体结构非常相似，因为供体分子被强烈二聚化，并且二聚体沿着沿着a轴构建一维柱。1·FeX 4和2·FeX 4之间的施主层的主要区别在于它们的二聚体内重叠模式，其分别为“环上键”和“环上原子”类型。正如预期的那样，反阴离子FeX 4-位于弯曲供体分子的中心部分附近，并形成沿着a轴的一维均匀链。在1·FeX 4和2·FeX 4中，供体分子与FeX 4 −离子之间存在紧密接触，尽管接触数量和接触距离都有显着差异。FeX 4 −离子的Fe（III）d自旋受到反铁磁相互作用的影响，1·FeBr 4和2·FeBr 4分别在8 K和5 K左右出现反铁磁有序。用扩展的Huckel方法计算了施主π电子与FeX 4 −离子d自旋之间的磁交换相互作用，表明间接π-d相互作用在1·FeBr 4和2·FeBr 4的反铁磁有序中起着重要作用.
The 1 : 1 cation-radical salts of the bent donor molecules ethylenedioxy(-ethylenedithio-)trimethylene-tetrathiafulvalenothioquinone-1,3-dithiolemethides [EDO-CP-TTFVS (1) and EDT-CP-TTFVS (2)] with an FeX4− (X = Cl, Br) ion, 1·FeX4 and 2·FeX4, were obtained as black, plate-like single crystals. Three of them, 1·FeCl4, 2·FeCl4 and 2·FeBr4, were prepared by electrochemical oxidation of 1 and 2 in the presence of Bu4N·FeX4 (X = Cl, Br), while 1·FeBr4 was prepared by chemical oxidation of 1 with FeBr3. All of these salts show semiconducting behaviour. The 2·FeX4 salts have relatively good electrical conductivities of about 0.1 S cm−1 at room temperature, which is around 100 times higher than those of 1·FeX4. The crystal structures of these four salts are very similar, in that the donor molecules are strongly dimerized and the dimers construct one-dimensional columns along the a-axis. The main difference in the donor layers between 1·FeX4 and 2·FeX4 is their intradimer overlap modes, which are the “ring-over-bond” and “ring-over-atom” types, respectively. The counter-anions FeX4− are located close to the central part of the bent donor molecules as expected, and form the one-dimensional, uniform chain along the a-axis. There are close contacts between the donor molecules and the FeX4− ions in both 1·FeX4 and 2·FeX4 although with significant differences in both contact number and contact distance. The Fe(III) d-spins of the FeX4− ions are subject to antiferromagnetic interactions, and antiferromagnetic ordering is found at around 8 K and 5 K for 1·FeBr4 and 2·FeBr4, respectively. The magnetic-exchange interactions between π-electrons of the donor and the d-spins of the FeX4− ions are calculated by an extended Huckel method, which demonstrates that the indirect π–d interactions play an important role in the antiferromagnetic ordering in 1·FeBr4 and 2·FeBr4.