Two solid phases of pyrimidin-1-ium hydrogen chloranilate monohydrate determined at 225 and 120 K
Two solid phases of pyrimidin-1-ium hydrogen chloranilate monohydrate determined at 225 and 120 K
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在 225 和 120 K 下测定的嘧啶-1-鎓氢氯苯甲酸盐一水合物的两个固相
DOI：
10.1107/s010827011000363x
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
Tetsuo Asajiand Hiroyuki Ishida
中科院分区：
文献类型：
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作者：
Kazuma Gotoh;Tetsuo Asajiand Hiroyuki Ishida
标题化合物C4H5N2+·C6HCl2O4−·H2O两种固相的晶体结构在225和120 K时被测定。在高温相中，稳定在198 K以上，其转变温度已由35Cl核四极共振和差热分析测量确定，三种组分通过O - H⋯O， N⋯H⋯O， C-H⋯O和C-H⋯Cl氢键结合在一起，形成中心对称的2+2+2聚集体。在嘧啶-1-ium阳离子与水分子之间形成的N⋯H⋯O氢键中，H原子在两个位置上无序，产生两种状态，即嘧啶-1-ium -水和嘧啶-氧鎓。在低温阶段，标题化合物在相同的单斜空间群中结晶，具有相似的分子堆积，但2+2+2聚集体失去了中心对称性，导致单位胞加倍，并且不对称单元中的每个组分具有两个晶体独立的分子。嘧啶-1-ium阳离子与水分子之间的一个N⋯H⋯O氢键中的H原子是无序的，而另一个氢键中的H原子在N原子位置上是有序的，具有较长的N- H距离[1.10 (3)Å]。
The crystal structures of two solid phases of the title compound, C4H5N2+·C6HCl2O4−·H2O, have been determined at 225 and 120 K. In the high-temperature phase, stable above 198 K, the transition temperature of which has been determined by 35Cl nuclear quadrupole resonance and differential thermal analysis measurements, the three components are held together by O—H⋯O, N⋯H⋯O, C—H⋯O and C—H⋯Cl hydrogen bonds, forming a centrosymmetric 2+2+2 aggregate. In the N⋯H⋯O hydrogen bond formed between the pyrimidin-1-ium cation and the water molecule, the H atom is disordered over two positions, resulting in two states, viz. pyrimidin-1-ium–water and pyrimidine–oxonium. In the low-temperature phase, the title compound crystallizes in the same monoclinic space group and has a similar molecular packing, but the 2+2+2 aggregate loses the centrosymmetry, resulting in a doubling of the unit cell and two crystallographically independent molecules for each component in the asymmetric unit. The H atom in one N⋯H⋯O hydrogen bond between the pyrimidin-1-ium cation and the water molecule is disordered, while the H atom in the other hydrogen bond is found to be ordered at the N-atom site with a long N—H distance [1.10 (3) Å].