Phase polymorphism of novel [Ru(NH₃)₆](ClO₄)₃¡ªComparison with [Ru(NH₃)₆](BF₄)₃. Part II

详细信息    查看全文

• 作者：Diana Do??ga ; Edward Mikuli ; Natalia G¨®rska ; Akira Inaba ; Krystyna Ho?derna-Natkaniec ; Wojciech Nitek
• 关键词：Hexaammineruthenium(III) chlorate(VII) ; Phase transitions ; Molecular dynamics ; Calorimetry ; XRSCD ; NMR
• 刊名：Journal of Solid State Chemistry
• 出版年：2013
• 出版时间：August, 2013
• 年：2013
• 卷：204
• 期：Complete
• 页码：233-244
• 全文大小：4611 K

文摘

[Ru(NH₃)₆](ClO₄)₃ undergoes two phase transitions at: T_C1=290.3 K and T_C2=74.8 K , thus exhibits three crystalline phases in the temperature range of 5-310 K. For the detected phase transitions, thermal effects were determined. Fourier transform far- and middle-infrared spectra (FT-FIR and FT-MIR), recorded at 8-350 K, suggest that reorientational motions of the NH₃ ligands are very fast (¦Ó_R¡Ö10^?12 s above T_C1) and are significantly slowed down below T_C2. X-ray single crystal diffraction (XRSCD) measurements revealed that in the high temperature phase (above T_C1) the compound belongs to the cubic Fmm (No. 225) space group, whereas in the intermediate phase the unit cell parameter doubles and the space group is Ia(No. 206). ¹H NMR studies revealed that the following reorientational motions are liberated during heating: three-fold reorientation of NH₃ ligands, three-fold reorientation of the entire [Ru(NH₃)₆]³⁺ cation, and isotropic reorientation of this cation. In the high temperature phase I the cations perform isotropic reorientations with the estimated activation energy equal to ca. 30.1 kJ mol^?1. Comparison with adequate results obtained earlier for [Ru(NH₃)₆](BF₄)₃ and for other similar compounds was made and general regularities were drawn.