Bipyrimidine‐Bridged Dinuclear Iron(II) Spin Crossover Compounds
Bipyrimidine‐Bridged Dinuclear Iron(II) Spin Crossover Compounds
复制标题
双嘧啶桥联双核铁(II)自旋交叉化合物
DOI：
10.1002/chin.200527226
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
H. Spiering
中科院分区：
文献类型：
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作者：
J. Real;A. Gaspar;M. Muñoz;P. Gütlich;V. Ksenofontov;H. Spiering
本文报道了2,2'-联嘧啶(bpym)-桥接铁（II）双核化合物中磁偶联与自旋跃迁之间相互作用的研究。在热、压力或电磁辐射等外部物理扰动作用下，在{[Fe(bpym)(NCS) 2] 2 (bpym)}、{[Fe(bpym)(NCSe) 2] 2 (bpym)}和{[Fe(bt)(NCS) 2] 2 (bpym)} （bpym=2,2'-联嘧啶，bt =2,2'-双噻唑啉）中观察到这两种现象的共存。在0.63 GPa下，研究了{[Fe(bpym)(NCS) 2] 2 (bpym)}中磁交换和自旋交叉的竞争。在4.2 K下对{[Fe(bpym)(NCSe) 2] 2 (bpym)}和{[Fe(bt)(NCS) 2] 2 (bpym)}进行的LIESST实验表明，在这类化合物中可以生成具有不同自旋态的双核分子。迄今为止所研究的双核化合物中自旋交叉过程的一个特点是自旋过渡曲线的平台。到目前为止，由于过渡发生的温度相对较高，用微观物理方法探索构成这样一个高原的物种的性质是不可能的。{[Fe(phdia)2(NCS) 2] 2(phdia)} （phdia: 4,7-菲罗啉-5,6-二胺）在t1 / 2(1)和t1 / 2(2)分别位于108 K和80 K时发生了两步自旋跃迁。由于这种低温转变，我们能够在液氦温度下，热捕获存在于自旋转变曲线平台上的物质。结果表明，平台主要由[HS-LS]对组成，他们证实了先前提出的双核实体中的自旋转换是通过[HS-HS]↔[HS-LS]↔[LS-LS]对进行的假设。
This review reports on the study of the interplay between magnetic coupling and spin transition in 2,2'-bipyrimidine (bpym)-bridged iron(II) dinuclear compounds. The coexistence of both phenomena has been observed in {[Fe(bpym)(NCS) 2 ] 2 (bpym)}, {[Fe(bpym)(NCSe) 2 ] 2 (bpym)} and {[Fe(bt)(NCS) 2 ] 2 (bpym)} (bpym=2,2'-bipyrimidine, bt = 2,2'-bithiazoline) by the action of external physical perturbations such as heat, pressure or electromagnetic radiation. The competition between magnetic exchange and spin crossover has been studied in {[Fe(bpym)(NCS) 2 ] 2 (bpym)} at 0.63 GPa. LIESST experiments carried out on {[Fe(bpym)(NCSe) 2 ] 2 (bpym)}and {[Fe(bt)(NCS) 2 ] 2 (bpym)}at 4.2 K have shown that it is possible to generate dinuclear molecules with different spin states in this class of compounds. A special feature of the spin crossover process in the dinuclear compounds studied so far is the plateau in the spin transition curve. Up to now, it has not been possible to explore with a microscopic physical method the nature of the species which constitute such a plateau, due to the relatively high temperatures at which the transition takes place. A two-step spin transition has been -observed for {[Fe(phdia)2(NCS) 2 ] 2 (Phdia)} (phdia: 4,7-phenanthroline-5,6-diamine) with T 1 / 2 (1) and T 1 / 2 (2) located at 108 and 80 K, respectively. Due to this low temperature transition we were able to thermally trap, at liquid helium temperatures, the species present in the plateau of the spin transition curve. The results have revealed that the plateau consists mainly of [HS-LS] pairs, and they confirmed the hypothesis formulated earlier that the spin conversion in dinuclear entities proceeds via [HS-HS]↔[HS-LS]↔[LS-LS] pairs.