A novel series of pyrrole-2-yl chloromethyl ketones were synthesized and studied by FT-IR, 1H, 13C NMR spectroscopy and DFT calculations at the B3LYP/6-311++G(d,p) level of approximation. Two stable conformations were detected in solution: s-cis and s-trans forms where the CO group is located on the same side or the opposite side of N–H group, respectively. The conformational stability of these molecules is governed mainly by intermolecular hydrogen bonding interactions. The strength of hydrogen bonds was evaluated on the basis of 1H chemical shift and infrared red shift ΔνN–H of the stretching vibration of N–H proton donating bonds. The quantum theory of ‘atoms in molecules’ as well as the natural bond orbital method were applied to characterize hydrogen bonding interactions.
合成了一系列新型
吡咯-2-基
氯甲基酮,并通过FT-IR、1H和13C NMR光谱以及DFT计算(在B3LYP/6-311++G(d,p)近似
水平)进行了研究。在溶液中检测到两种稳定构象:s-cis和s-trans形式,其中CO基团分别位于N–H基团的同侧或对侧。这些分子的构象稳定性主要由分子间氢键相互作用所主导。氢键的强度是基于1H
化学位移和N–H质子供体键的伸缩振动红外红移ΔνN–H进行评估的。采用“分子中的原子”量子理论以及自然键轨道方法来表征氢键相互作用。