Laboratoire de Chimie de Coordination, CNRS UPR-8241, and Université de Toulouse, UPS, INP, Toulouse, France.
Phys Chem Chem Phys. 2012 Apr 21;14(15):5265-71. doi: 10.1039/c2cp23940j. Epub 2012 Mar 8.
The effect of pressure on the dinuclear spin crossover material [{Fe(bpp)(NCS)(2)}(2)(4,4'-bipy)]·2MeOH (where bpp = 2,6-bis(pyrazol-3-yl)pyridine and 4,4'-bipy = 4,4'-bipyridine, 1) has been investigated with single crystal X-ray diffraction and Raman spectroscopy using diamond anvil cell techniques. The very gradual pressure-induced spin crossover occurs between 7 and 25 kbar, and shows no evidence of crystallographic phase transitions. The pressure-induced spin transition leads to a complete LS state which is not thermally accessible. This structural evolution under pressure is in stark contrast to the previously reported thermal spin crossover behaviour, in which a symmetry-breaking, purely structural phase transition results in only partial conversion to the low spin state. This observation is attributed to the symmetry-breaking phase transition becoming unfavourable under pressure.
用金刚石压腔技术结合单晶 X 射线衍射和拉曼光谱研究了压力对双核自旋交叉材料 [{Fe(bpp)(NCS)(2)}(2)(4,4'-bipy)]·2MeOH（其中 bpp = 2,6-双(吡唑-3-基)吡啶，4,4'-bipy = 4,4'-联吡啶，1）的影响。非常缓慢的压力诱导自旋交叉发生在 7 到 25 kbar 之间，并且没有证据表明存在结晶相转变。压力诱导的自旋转变导致完全的 LS 态，该态在热学上不可用。这种压力下的结构演化与先前报道的热自旋交叉行为形成鲜明对比，在热自旋交叉行为中，对称性破缺的纯结构相转变仅导致部分转化为低自旋态。这种观察结果归因于对称性破缺相转变在压力下变得不利。
