Single-crystal X-ray diffraction datasets for the low-temperature phase of hypoxantinium nitrate hydrate

The crystals of the title compound were investigated by means of X-ray diffraction at ten different temperatures in the range of 20 K to 220 K. The dataset contains twenty zip files: _raw with unprocessed diffraction data from hypoxanthinium nitrate hydrate. _model with the final structure model obtained from the raw data. ##Crystallization The 0.05 g of pure hypoxanthine (powder, Sigma-Aldrich) was dissolved in a solution consisting of 30 ml of distilled water and 5.2 ml of 65% nitric acid. The beaker with the mixture was left covered with parafilm under a fume hood for three days, after which the crystals appeared. ##Data collection The data were collected using Agilent Technologies SuperNova four-circle diffractometer equipped with a micro-focus sealed tube and Eos CCD detector. The temperature was controlled by Oxford Cryosystems low-temperature nitrogen gas-flow device. The 20K temperature was provided by CRYOCOOL-LHe gas stream cooler. ##Structure solution and refinement The determination of unit cell, data reduction and absorption correction were performed in software provided with the diffractometer - using CrysAlis PRO Version 1.171.38.46. The structure solution and refinement was performed within Olex2 graphical environment. For the solution ShelXT with intrinsic phasing was used. For refinement ShelXL with least squares. Almost all hydrogen atoms were located in the difference map and refined freely – in cases where free refinement was not possible, the hydrogens were refined as riding on their respective heavy atom. ##Model description The hypoxanthinium nitrate hydrate crystallizes in P21/n space group, and is a non-merohedral twin with the second twin domain rotated by 180° around the a axis with respect to the original lattice. The asymmetric unit contains one hypoxanthinium cation, nitrate anion and water molecule.

本研究采用X射线衍射（X-ray diffraction）技术，在20 K至220 K的温度范围内，于10个不同温度点下对标题化合物的晶体开展了表征。本数据集包含20个压缩文件：_raw 文件夹存储硝酸次黄嘌呤水合物的未处理衍射数据，_model 文件夹存储由原始数据解析得到的最终结构模型。

### 结晶过程
称取0.05 g 纯次黄嘌呤（粉末，Sigma-Aldrich品牌），将其溶解于由30 mL 蒸馏水与5.2 mL 65%硝酸组成的混合溶液中。将盛有该混合液的烧杯用parafilm封口膜覆盖后，置于通风橱内静置三日，期间析出目标晶体。

### 数据采集
数据采集使用安捷伦科技（Agilent Technologies）SuperNova 四圆衍射仪，该仪器配备微焦点密封靶管与Eos CCD探测器。温度控制采用Oxford Cryosystems 低温氮气气流装置；20 K的温度条件则通过CRYOCOOL-LHe 氦气流冷却器实现。

### 结构解析与精修
晶胞参数测定、数据约简与吸收校正均使用衍射仪配套软件CrysAlis Pro 版本1.171.38.46 完成。结构解析与精修工作在Olex2 图形化环境中开展：结构解析采用ShelXT 本征相位法，精修则采用ShelXL 最小二乘法。绝大多数氢原子可通过差分傅里叶图定位并自由精修；对于无法自由精修的氢原子，则将其约束于对应重原子上进行骑乘式精修。

### 模型描述
硝酸次黄嘌呤水合物晶体属于P2₁/n 空间群，为非整比孪晶（non-merohedral twin），其第二孪晶畴相对于原始晶格沿a轴旋转180°。该晶体的不对称单元包含1个次黄嘌呤阳离子、1个硝酸根阴离子与1个水分子。