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由于多氟烯烃化合物中氟原子的强的电子效应,使得烯基氟的~(19)F化学位移参数与该烯烃的电荷密度分布有密切的联系。它在一定程度上反映了多氟烯烃在亲核反应中的化学反应性。这在某种意义上来说加深了对多氟烯烃结构及化学反应性的认识。一、多氟烯烃电荷密度与~(19)F化学位移的关系 Spiesecke和Schneider在1961年首次发表了C_5H_5~-,C_6H_6,C_7H_7~+上碳原子的π电子电荷密度与~(13)C、~(1)H化学位移的关系。他们测定了C_5H_5~-,C_6H_6,C_7H_7~+的~(13)C、~1H的化学位移,再根据早就为人们所熟知的Huckel分子轨道理论计算得到的共轭分子π电荷的
Due to the strong electronic effect of fluorine atoms in the polyfluoroolefin compounds, the ~ (19) F chemical shift parameters of the alkenyl fluorine are closely related to the charge density distribution of the olefin. It partly reflects the chemical reactivity of polyfluoroolefins in the nucleophilic reaction. This in some ways deepens our understanding of the structure and chemical reactivity of polyfluoroolefins. First, the charge density of polyfluoroolefin and ~ (19) F chemical shift relationship Spiesecke and Schneider first published in 1961 C_5H_5 ~ -, C_6H_6, C_7H_7 ~ + carbon atoms on the π electron charge density and ~ (13) C, ~ (1) H chemical shift relationship. They measured the chemical shifts of ~ (13) C, ~ 1H for C_5H_5 ~ -, C_6H_6, and C_7H_7 ~ +, and calculated their π charges based on the well-known Huckel molecular orbital theory