bonds and the elongation of the C–H bond participating in hydrogen bonds estimated by the PM3 and BLYP/6-31G(d,p) calculations. The UV spectra and 1 H NMR spectra of selected ylides have been measured. The solvent effect on the proton chemical shifts of quaternary pyridinium halides and ylides is discussed. Semiempirical and DFT calculations were carried out to investigate the structure of ylides. In ylides
摘要 在含有强碱(
DBU、
MTBD 和 P1-tBu)的
DMSO 溶液中测量了八种含有活化亚甲基的季
吡啶盐与相应的叶立德的平衡速率。环取代基对去质子化速率的影响大于亚甲基取代基的影响。这一观察结果与通过 PM3 和 BLYP/6-31G(d,p) 计算估计的 C-H⋯N 氢键的能量和参与氢键的 C-H 键的伸长率一致。已测量所选叶立德的紫外光谱和 1 H NMR 光谱。讨论了溶剂对季
铵卤化物和叶立德的质子
化学位移的影响。进行了半经验和 DFT 计算以研究叶立德的结构。在叶立德,