The synthesis and structural characterization of novel amine-borane adducts of ibuprofen derivatives are presented. The changes of the electron density on the carbonyl and pyridine ring after formation of N→BH3, N→BF3, and N-CH3+ have been confirmed by 1H, 11B, 13C, and 19F NMR, further supported by homonuclear and heteronuclear correlations. Moreover, electrostatic interactions —H+···−F and the nonclassical H+···−H— were identified by NMR spectra. The analysis of the resulting molecular structures offered insights on the 2-aminopyridine N→B adducts. The N→BH3 adduct formed a single molecular arrangement, both in C6D6 and CDCl3. The same behavior was observed for the N→BF3 adduct in CDCl3. However, two conformers of this adduct were detected in C6D6. All adduct geometries were corroborated by density functional theory computational calculations.

中文翻译：

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N→BH3 、N→BF3 和 N-CH3 + 复合物与布洛芬衍生酰胺的构象分析

介绍了布洛芬衍生物的新型胺-硼烷加合物的合成和结构表征。N→BH3、N→BF3和N-CH3+形成后羰基和吡啶环上电子密度的变化已被1H、11B、13C和19F核磁共振证实，并得到同核和异核相关性的进一步支持。此外，静电相互作用-H+...-F 和非经典的H+...-H- 通过NMR 光谱进行了鉴定。对所得分子结构的分析提供了对 2-氨基吡啶 N→B 加合物的见解。N→BH3 加合物在 C6D6 和 CDCl3 中形成单一分子排列。对 CDCl3 中的 N→BF3 加合物观察到相同的行为。然而，在 C6D6 中检测到该加合物的两个构象异构体。所有加合物几何形状都通过密度泛函理论计算计算得到证实。