The salts of 1,4-diazabicyclo[2.2.2]octane (DABCO) and bis(trifluoromethylsulfonyl)amine (in 1â:â1 and 1â:â2 stoichiometry, 1 and 2, respectively) were investigated by DSC, TGA, PXRD and single crystal X-ray diffraction. Thermal analysis of the two compounds revealed reversible phase transitions, indicating enantiotropic relationships between all the polymorphs. Compound 1 can exist as a room-temperature form 1L and as a high-temperature modification 1H. By contrast, 2 forms a low- (2L), an intermediate- (2I) and a high-temperature (2H) polymorph. The structures of 1L and 2L were determined by single crystal X-ray crystallography. NâHâ¯O bonded cations of 1L are arranged in a staggered fashion and form infinite chains. The crystal contains two sets of symmetry related H-bonded chains, which are in an inclined orientation relative to one another. In the structure of 2L, the cation is NâHâ¯O bonded to two neighbouring triflimide anions. The discrete H-bonded structure fragments resulting from these interactions assemble to a layer structure. The structure determination of the high-temperature forms 1H and 2H from PXRD data was negatively affected by a high degree of disorder of the triflimide anions. All NâHâ¯O bonded DABCO chains in 1H adopt a parallel orientation, which is in contrast to the inclined orientation found in 1L.
通过
DSC、TGA、PXRD 和单晶 X 射线衍射,研究了 1,4-二氮杂
双环[2.2.2]辛烷 (
DABCO) 和双(三
氟甲基磺酰基)胺(分别为 1:1 和 1:2)的盐。这两种化合物的热分析显示出可逆的相变,表明所有多晶体之间存在对映关系。化合物 1 可以室温形式 1L 和高温形式 1H 存在。相比之下,化合物 2 可形成低温(2L)、中温(2I)和高温(2H)多晶型。1L 和 2L 的结构是通过单晶 X 射线晶体学确定的。1L 的 NâHâ¯O 键阳离子交错排列,形成无限链。晶体中包含两组对称性相关的 H 键链,这两组 H 键链相互之间呈倾斜方向。在 2L 的结构中,阳离子以 NâHâ¯O 键与两个相邻的三亚甲基阴离子结合。这些相互作用产生的离散 H 键结构片段组合成层状结构。根据 PXRD 数据确定高温形式 1H 和 2H 的结构受到了三
氟甲基阴离子高度无序性的负面影响。1H 中的所有 NâHâ¯O 键
DABCO 链都呈平行取向,这与 1L 中的倾斜取向形成了鲜明对比。