Room Temperature Magnetic Switchability Assisted by Hysteretic Valence Tautomerism in a Layered Two-Dimensional Manganese-Radical Coordination Framework
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- 作者：Anthony Lannes ; Yan Suffren ; Jean Bernard Tommasino ; Rodica Chiriac ; François Toche ; Lhoussain Khrouz ; Florian Molton ; Carole Duboc ; Isabelle Kieffer ; Jean-Louis Hazemann ; Christian Reber ; Andreas Hauser ; Dominique Luneau
- 刊名：Journal of the American Chemical Society
- 出版年：2016
- 出版时间：December 21, 2016
- 年：2016
- 卷：138
- 期：50
- 页码：16493-16501
- 全文大小：707K
- ISSN：1520-5126
文摘
The manganese-nitronyl-nitroxide two-dimensional coordination polymer {[Mn2(NITIm)3]ClO4}n (1) (NITImH = 2-(2-imidazolyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-3-oxide-1-oxyl) undergoes an unusual hysteretic thermo-induced valence tautomeric transition near room temperature, during which the manganese(II) ions are oxidized to manganese(III) and two of the three deprotonated radicals (NITIm–) are reduced to their diamagnetic aminoxyl form (denoted NITRed2–). Upon cooling, the high-temperature species {[MnII2(NITIm)3]ClO4}n (1HT) turns into the low-temperature species {[MnIII2(NITRed)2(NITIm)]ClO4}n (1LT) around 274 K, while on heating the process is reversed at about 287 K. This valence tautomeric phenomenon is supported by temperature-dependent magnetic susceptibility measurements, differential scanning calorimetry (DSC), crystal structure determination, UV–vis absorption, X-ray absorption (XAS), and emission (XES) and electron paramagnetic resonance (EPR) spectroscopies in the solid state.