Trimethoprim crystallizes in the triclinic space group P-1 (#2) with a = 10.5085(3), b = 10.5417(2), c = 8.05869(13) Å, α = 101.23371(21), β = 112.1787(3), γ = 112.6321(4)°, V = 743.729 Å3, and Z = 2. A reduced cell search in the Cambridge Structural Database yielded three previous structure determinations, using data collected at 100 K, 173 K, and room temperature. In this work, the sample was ordered from the United States Pharmacopeial Convention (USP) and analyzed as-received. The room temperature (295 K) crystal structure was refined using synchrotron (λ = 0.412826 Å) powder diffraction data and optimized using density functional theory techniques. We found similar hydrogen bonding patterns with the previous determinations. In addition, we identified two C–H⋯O hydrogen bonds, which also contribute to the crystal energy. When comparing the previously reported trimethoprim structure determinations, the unit cell length lattice parameters were found to contract at lower temperatures, particularly 100 K. All structures show reasonable agreement, with unit cell length differences ranging between 0.05 and 0.15 Å. The diffraction data for this study were collected on beamline 11-BM at the Advanced Photon Source, and the powder X-ray diffraction pattern of the compound has been submitted to ICDD® for inclusion in the Powder Diffraction File™ (PDF®).

中文翻译：

---

甲氧苄啶 I 型 C14H18N4O3 的粉末 X 射线衍射

甲氧苄啶在三斜空间群中结晶磷-1 (#2) 与一种= 10.5085(3),b= 10.5417(2),C= 8.05869(13) 埃，α= 101.23371(21),β= 112.1787(3),γ= 112.6321(4)°,五= 743.729 Å3，和Z= 2. 使用在 100 K、173 K 和室温下收集的数据，剑桥结构数据库中的简化单元搜索产生了三个先前的结构测定。在这项工作中，样品是从美国药典公约 (USP) 订购的，并按原样进行分析。室温（295 K）晶体结构使用同步加速器（λ= 0.412826 Å) 粉末衍射数据并使用密度泛函理论技术进行优化。我们发现与先前的测定相似的氢键模式。此外，我们确定了两个 C-H⋯O 氢键，这也有助于晶体能量。在比较先前报道的甲氧苄啶结构测定时，发现晶胞长度晶格参数在较低温度下收缩，特别是 100 K。所有结构都显示出合理的一致性，晶胞长度差异在 0.05 和 0.15 Å 之间。本研究的衍射数据是在 Advanced Photon Source 的光束线 11-BM 上收集的，化合物的粉末 X 射线衍射图已提交给 ICDD® 以包含在 Powder Diffraction File™ (PDF®) 中。