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利用理论方法研究了乙醛二聚体内的氢键.在MP2/6-31+G(d),B3LYP/6-31+G(d),B3LYP/6-311++G(d,p)和B3LYP/6-311++G(3df,2p)水平上,利用常规方法和均衡校正方法对3种稳定的乙醛二聚体进行了几何优化和振动频率计算.计算结果表明:在二聚体A和C中乙醛中C—H键强烈收缩,存在显著的C—H…O蓝移型氢键.自然键轨道(NBO)分析表明,电子供体轨道和电子受体轨道之间相互作用的稳定化能、分子内电子密度重排、轨道再杂化和结构重组是决定氢键红移和蓝移的主要因素.其中,轨道间稳定化能属于键伸长效应,分子内电子密度重排、轨道再杂化和电子受体内部结构重组属于键收缩效应.在二聚体A和C中,由于键收缩效应处于优势地位导致C—H…O蓝移氢键存在.
The hydrogen bonds in the acetaldehyde dimer were studied theoretically. The results showed that the hydrogen bonds in the acetaldehyde dimer were the best. And B3LYP / 6-311 ++ G (3df, 2p), the geometric and vibrational frequencies of three stable acetaldehyde dimers were calculated by the conventional method and the equilibrium calibration method. The calculated results show that in dimerization The C-H bond in acetaldehyde strongly shrunk in both A and C, and there was a significant C-H ... O blue shift type hydrogen bond. The analysis of NBO showed that the interaction between electron donor and electron acceptor orbitals The stabilizing energy, intramolecular electron density rearrangement, orbital recombination and structural recombination are the main factors that determine the red-shift and blue-shift of hydrogen bonds, among which the orbital stabilization can belong to the bond elongation effect, the intramolecular electron density Rearrangement, orbital recombination and recombination of internal structures of electron acceptors are key shrinkage effects. In dimers A and C, C-H ... O blue shift hydrogen bonds are present due to the predominance of the bond shrinkage effect.