Abstract The ibuprofen derivative 5-(1-(4-isobutylphenyl)ethyl)-1,3,4-thiadiazol-2-amine hydrochloride is prepared by via cyclization of ibuprofen with thiosemicarbazide in the presence of POCl3. The compound has been characterized by using FT-IR and multinuclear (1H and 13C) NMR spectroscopies, and elemental analysis. The molecular structure in crystalline phase has been determined by single crystal X-Ray diffraction. The compound crystallizes in the triclinic system with space group P-1 as discrete cations and chloride anions with two enantiomers present in the asymmetric unit. A full vibrational analysis of the FT-IR and FT-Raman spectra has been performed in conjunction with quantum chemical calculations. Experimental data agree with the occurrence of the thiadiazole N H protonated form in the solid phase. The observation of the ν(N N) and δ(CNN) normal modes as strong signals in the infrared and Raman spectra at 1189 (1180 cm−1) and 774 cm−1 suggests a N N bond with partial double bond character in the thiadiazole moiety, in good agreement with the computed values at the B3LYP/6-311++G(d,p) level of approximation. The NBO analysis showed that both, the sulfur lone pair and the exocyclic amine nitrogen lone pair orbitals contribute to strong resonance interactions with the adjacent π*(N2=C8) antibonding orbital of the protonated thiadiazole group.

中文翻译：

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布洛芬-噻二唑杂化化合物：5-(1-(4-异丁基苯基)乙基)-1,3,4-噻二唑-2-胺盐酸盐的合成、振动分析和分子结构

摘要 布洛芬衍生物5-(1-(4-异丁基苯基)乙基)-1,3,4-噻二唑-2-胺盐酸盐由布洛芬与氨基硫脲在POCl3存在下环化制备。该化合物已通过使用 FT-IR 和多核（1H 和 13C）NMR 光谱和元素分析进行​​表征。结晶相中的分子结构已通过单晶 X 射线衍射确定。该化合物在三斜晶系中结晶，空间群 P-1 作为离散的阳离子和氯阴离子，在不对称单元中存在两种对映异构体。结合量子化学计算对 FT-IR 和 FT-拉曼光谱进行了完整的振动分析。实验数据与固相中噻二唑 NH 质子化形式的出现一致。在 1189 (1180 cm-1) 和 774 cm-1 处观察到 ν(NN) 和 δ(CNN) 法向模式作为强信号在红外和拉曼光谱中表明在噻二唑部分存在具有部分双键特征的 NN 键，与 B3LYP/6-311++G(d,p) 近似水平的计算值非常一致。NBO 分析表明，硫孤对和环外胺氮孤对轨道都有助于与质子化噻二唑基团的相邻 π*(N2=C8) 反键轨道的强共振相互作用。