Martínez Víctor, Gaspar Ana Belén, Muñoz M Carmen, Bukin Gennadiy V, Levchenko Georgii, Real José Antonio
Institut de Ciència Molecular (ICMol)/Departament de Química Inorgánica, Universitat de València, Edifici d'Instituts de Paterna, Apartat de Correus 22085, 46071 València, Spain.
Chemistry. 2009 Oct 19;15(41):10960-71. doi: 10.1002/chem.200901391.
Twelve coordination polymers with formula {Fe(3-Xpy)(2)[M(II)(CN)(4)]} (M(II): Ni, Pd, Pt; X: F, Cl, Br, I; py: pyridine) have been synthesised, and their crystal structures have been determined by single-crystal or powder X-ray analysis. All of the fluoro and iodo compounds, as well as the chloro derivative in which M(II) is Pt, crystallise in the monoclinic C2/m space group, whereas the rest of the chloro and all of the bromo derivatives crystallise in the orthorhombic Pnc2 space group. In all cases, the iron(II) atom resides in a pseudo-octahedral [FeN(6)] coordination core, with similar bond lengths and angles in the various derivatives. The major difference between the two kinds of structure arises from the stacking of consecutive two-dimensional {Fe(3-Xpy)(2)[M(II)(CN)(4)]}(infinity) layers, which allows different dispositions of the X atoms. The fluoro and chloro derivatives undergo cooperative spin crossover (SCO) with significant hysteretic behaviour, whereas the rest are paramagnetic. The thermal hysteresis, if X is F, shifts toward room temperature without changing the cooperativity as the pressure increases in the interval 10(5) Pa-0.5 GPa. At ambient pressure, the SCO phenomenon has been structurally characterised at different significant temperatures, and the corresponding thermodynamic parameters were obtained from DSC calorimetric measurements. Compound {Fe(3-Clpy)(2)[Pd(CN)(4)]} represents a new example of a "re-entrant" two-step spin transition by showing the Pnma space group in the intermediate phase (IP) and the Pnc2 space group in the low-spin (LS) and high-spin (HS) phases.
已合成了十二个化学式为{Fe(3-Xpy)(2)[M(II)(CN)(4)]}（M(II)：Ni、Pd、Pt；X：F、Cl、Br、I；py：吡啶）的配位聚合物，并通过单晶或粉末X射线分析确定了它们的晶体结构。所有的氟化物和碘化物，以及M(II)为Pt的氯衍生物，都结晶于单斜C2/m空间群，而其余的氯衍生物和所有的溴衍生物都结晶于正交Pnc2空间群。在所有情况下，铁(II)原子位于一个伪八面体[FeN(6)]配位核心中，在各种衍生物中具有相似的键长和键角。两种结构之间的主要差异源于连续二维{Fe(3-Xpy)(2)[M(II)(CN)(4)]}(infinity)层的堆积，这使得X原子有不同的排列方式。氟化物和氯化物衍生物经历具有显著滞后行为的协同自旋交叉（SCO），而其余的则是顺磁性的。当压力在10(5) Pa - 0.5 GPa范围内增加时，如果X为F，热滞会向室温移动而不改变协同性。在常压下，已在不同的重要温度下对SCO现象进行了结构表征，并从DSC量热测量中获得了相应的热力学参数。化合物{Fe(3-Clpy)(2)[Pd(CN)(4)]}通过在中间相（IP）中显示Pnma空间群以及在低自旋（LS）和高自旋（HS）相中显示Pnc2空间群，代表了“重入”两步自旋转变的一个新例子。
