Low-Spin鈫扝igh-Spin Relaxation Dynamics in the Highly Diluted Spin-Crossover System [FexZn1鈭?i>x(bbtr)3](ClO4)2

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• 作者：Itana Krivokapic ; Pradip Chakraborty ; Cristian Enachescu ; Robert Bronisz ; Andreas Hauser
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：March 7, 2011
• 年：2011
• 卷：50
• 期：5
• 页码：1856-1861
• 全文大小：841K
• 年卷期：v.50,no.5(March 7, 2011)
• ISSN：1520-510X

文摘

Whereas the neat polymeric iron(II) compound [Fe(bbtr)₃](ClO₄)₂, bbtr = 1,4-di(1,2,3-triazol-1-yl)butane, shows a quantitative spin transition triggered by a crystallographic phase transition centered at 107 K with a 13 K wide hysteresis, the iron(II) complexes in the diluted mixed crystals [Fe_xZn_1鈭?i>x(bbtr)₃](ClO₄)₂, x = 0.02 and 0.1, stay predominantly in the ⁵T₂ high-spin state down to cryogenic temperatures. However, the ¹A₁ low-spin state can be populated as metastable state via irradiation into the spin-allowed ⁵T₂鈫?sup>5E ligand-field transition of the high-spin species in the near-infrared. The quantum efficiency of the light-induced conversion is approximately 10% at low temperatures and decreases rapidly above 160 K. The lifetime of the light-induced low-spin state decreases from 15 days at 40 K to 30 ns at 220 K, that is, by 14 orders of magnitude. In the high-temperature regime the activation energy for the low-spin鈫抙igh-spin relaxation is 1840(20) cm^鈭?.