Synthesis, magnetic and photomagnetic study of new iron(II) spin-crossover complexes with N₄O₂ coordination sphere.
Synthesis, magnetic and photomagnetic study of new iron(II) spin-crossover complexes with N₄O₂ coordination sphere.
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DOI：
10.1039/b925482j
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发表时间：
2010-05
影响因子：
4
通讯作者：
Li Zhang;Guancheng Xu;Hongbin Xu;V. Mereacre;Zheming Wang;A. Powell;Song Gao
中科院分区：
文献类型：
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作者：
Li Zhang;Guancheng Xu;Hongbin Xu;V. Mereacre;Zheming Wang;A. Powell;Song Gao
合成了一类新的中性单核铁(II)自旋交叉化合物：Fe(L？⁻⁶)₂=N‘-((吡啶-2-基)亚甲基)苯肼(HL？)，N’-(phenyl(pyridin-2-yl)methylene)benzohydrazide(HL？)，2-hydroxy-N‘-((pyridin-2-yl)methylene)benzohydrazide(HL？⁻⁶)₂)，⁻⁶？以含N，N，O给电子体的系列三齿席夫碱配体为原料，合成了含N-2-hydroxy-N‘-(1-(pyridin-2-yl)ethylidene)benzohydrazide(HL-O-2-hydroxy-N’-(phenyl(pyridin-2-yl)methylene)benzohydrazide)和N-₂-O给电子体的系列配体。对这些化合物的磁学性质的研究表明，在测量的温度范围内，化合物1处于高自旋(HS)态，化合物3和6主要处于低自旋(LS)态，而其他化合物表现出各种SCO性质：化合物2经历了特征温度T(1/2)高于350K的逐渐不完全的SCO；化合物4在~150K(光滑)和200K(两步，T(S1↑/↓)=204/202K和T(S2↑/↓)=227/219K)下表现出特殊的阶梯式热诱导SCO，在100K以下产生HS和LS态的混合物；化合物5表现出渐进和完整的LS↔HS SCO，特征温度T(1/2)=273K。三种SCO化合物都表现出不同程度的光诱导自旋态陷阱效应。为了深入分析这些行为，用穆斯堡尔谱和差示扫描量热法(DSC)对所有化合物在290K和110K的LS态的晶体结构进行了测定，证实了伴随着自旋转变的结构变化。此外，还提出了该体系的烷基取代对配位场的影响。
A new family of neutral mononuclear iron(II) spin crossover (SCO) compounds, Fe(L¹⁻⁶)₂ (L¹⁻⁶ = N'-((pyridin-2-yl)methylene)benzohydrazide (HL¹), N'-(1-(pyridin-2-yl)ethylidene)-benzohydrazide (HL²), N'-(phenyl(pyridin-2-yl)methylene)benzohydrazide (HL³), 2-hydroxy-N'-((pyridin-2-yl)methylene)benzohydrazide (HL⁴), 2-hydroxy-N'-(1-(pyridin-2-yl)ethylidene)benzohydrazide (HL⁵), 2-hydroxy-N'-(phenyl(pyridin-2-yl)methylene)benzohydrazide (HL⁶)) with N₄O₂ donor sets have been synthesized from series tridentate Schiff base ligands with N,N,O donor sets. The investigation of magnetic properties of these compounds reveal that in the measured temperature range, compound 1 is in the high-spin (HS) state, and compound 3 and 6 are mainly in the low-spin (LS) state, whereas the other compounds exhibit various SCO properties: compound 2 undergoes a gradual incomplete SCO with characteristic temperature T(1/2) higher than 350 K; compound 4 exhibits a special stepwise thermally induced SCO occurring at ~150 K (smooth) and 200 K (two-steps, with T(S1↑/↓) = 204/202 K and T(S2↑/↓) = 227/219 K) with a mixture of the HS and LS states yielded below 100 K; compound 5 shows a gradual and complete LS↔HS SCO with characteristic temperature T(1/2) = 273 K. All the three SCO compounds show the LIESST (light induced exited spin state trapping) effect with different levels of photoconversion. To thoroughly analyze these behaviours, Mössbauer spectra and DSC of 4 and 5, crystal structures of all the compounds at 290 K and 5 in the LS state at 110 K were carried out, which confirmed the structural changes accompanying the spin transition. In addition, alkyl substitution effect on the ligand field was suggested for this system.