3-[1-[4-(2-Methylpropyl)phenyl]ethyl]-6-(4-fluorophenyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole (C21H21FN4S) has been synthesized as a member of a series of triazolothiadiazoles having NSAIDs moieties with cytotoxic activity. The crystal structure of this new compound has been solved and refined using conventional laboratory X-ray powder diffraction data and optimized using density functional techniques. The final structure solution was achieved by Rietveld refinement using soft restraints on all non-H atom bond lengths and angles. This compound crystallizes in $P\bar{1}\;$ space group, with the unit cell parameters a = 5.5880(4) Å, b = 9.3074(7) Å, c = 19.497(4) Å, α = 99.311(10)°, β = 91.925(9)°, γ = 98.199(6)°, and V = 988.8(2) Å3. To complement and verify the structure solution of the compound, the density functional theory (DFT) calculations were performed by using the local density approximation and the generalized gradient approximation for exchange-correlation energy. In order to see the effect of the van der Waals interactions on the electronic structure, the relevant structure was also optimized with B3LYP-D2, PBE-D2, and optB88-vdW functionals. The refined crystal structure was confirmed by the DFT calculations. The best agreement with the experimental structure was achieved by optB88-vdW functional.

中文翻译：

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3-[1-[4-(2-甲基丙基)苯基]乙基]-6-(4-氟苯基)-1,2,4-三唑并[3,4-b]-1,3的合成及结构表征， 4-噻二唑

3-[1-[4-(2-甲基丙基)苯基]乙基]-6-(4-氟苯基)-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑（C21H21FN4S) 已被合成为一系列三唑并噻二唑中的一员，这些三唑并噻二唑具有具有细胞毒活性的 NSAIDs 部分。这种新化合物的晶体结构已经使用常规实验室 X 射线粉末衍射数据进行了解析和改进，并使用密度泛函技术进行了优化。最终的结构解决方案是通过 Rietveld 细化实现的，该细化使用对所有非 H 原子键长和角度的软约束。该化合物结晶于$P\bar{1}\;$空间群，具有晶胞参数一种= 5.5880(4) 埃，b= 9.3074(7) 埃，C= 19.497(4) 埃，α= 99.311(10)°,β= 91.925(9)°,γ= 98.199(6)°，并且五= 988.8(2) Å3. 为了补充和验证化合物的结构解，使用交换相关能的局部密度近似和广义梯度近似进行密度泛函理论（DFT）计算。为了观察范德华相互作用对电子结构的影响，还使用 ​​B3LYP-D2、PBE-D2 和 optB88-vdW 泛函对相关结构进行了优化。精细的晶体结构通过 DFT 计算得到证实。optB88-vdW 函数实现了与实验结构的最佳一致性。