Thermal decomposition of trans-difluoro bis-(ethylenediamine) chromium (III) chloride 1.5 hydrate and μ-[(ethylenediamine) chromium (III) dichloro-(ethylenediamine)] chloride

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• 作者：Guindy ; Nabila M. ; Abou-Gamra ; Zeinab M. ; Abdel Messih ; Michel F.
• 关键词：Thermal decomposition ; Trans-difluoro bis-(ethylenediamine) chromium (III) chloride 1.5 hydrate ; μ ; -[(ethylenediamine) chromium (III) dichloro-(ethylenediamine)] chloride
• 刊名：Thermochimica Acta
• 出版年：1999
• 出版时间：December 14, 1999
• 年：1999
• 卷：340-341
• 期：Complete
• 页码：241-253
• 全文大小：444 K

文摘

Two complexes trans-difluoro bis-(ethylenediamine) chromium (III) chloride 1.5 hydrate and μ-[(ethylenediamine) chromium (III) dichloro (ethylenediamine)] chloride were isolated and were characterized by elemental analysis and IR spectroscopy. The thermal behaviour of the two complexes on heating up to 800°C in nitrogen atmosphere was examined by thermogravimetry (TG), DTG and differential thermal analysis (DTA). Thermal analysis showed three stages of decomposition of trans-[Cr(en)₂F₂]Cl·1.5H₂O in the following order: (i) dehydration, (ii) deamination or loss of amine and (iii) total disruption of the complex to form Cr₂O₃. As for [(Cr₂(en)₃Cl₄)]Cl₂, its decomposition involved: (i) loss of the bridged ethylenediamine, (ii) loss of the two other ethylene diamines and (iii) disruption of the complex to form the oxide. Activation parameters were evaluated using the theory of absolute reaction rate and values of activation energy were found to be 38.3 and 103 kJ mol⁻¹ for the dehydration and deamination of trans-[Cr(en)₂F₂]Cl·1.5H₂O respectively, and 88.7 and 203 kJ mol⁻¹ for the loss of bridged ethylene diamine and the other two ethylenediamines of [Cr₂(en)₃Cl₄]Cl₂ molecules, respectively.