含氟膦叶立德的^(13)C和^(31)P核磁共振研究

^(13)C and ^(31)P NMR Spectroscopies of Fluorinated Phosphoranes

利用^(13)C核磁共振可以研究化合物的电子结构,尤其是叶立德的电子结构和电荷分布,但膦叶立德^(13)C核磁共振的研究报道较少。Gray报道六个膦叶立德的^(13)C核磁共振研究,测定了化学位移和偶合常数,叶立德的~1J_(CP)在30％范围内变动。~1J_(CP)可以反映叶立德键的s-特性,随着~1J_(CP)的增加,s-特性亦增加。

The ^(13)C and ^(31)P NMR spectra of thirty-one fluorinated phosphoranes have been studied. The data are presented in Table 1. In fluorinated phosphoranes, the chemical shifts of the ylidic carbon have been found to be influenced by the substituents directly attached to the ylidic carbon, and have the following order: 4-GlC_6H4(or C_6H_5O), CHO, COSCH_3, COSCH_3, CO_2CH_3, α-C_4H_3S,P(O)(OC_6H_5)_2, C_6F_5, H, CN chemical shifts toward upfield → The coupling constant ~1J _(CP) which does reflect the s-character of the ylidic bond have also been found to be influenced by the nature of substituents directly attached to the ylidic carbon and have the following order: P(O)(OC_6H_5)_2, CHO, C0SCH_3(or H, CO_2CH_3, α-C_4H_3S), C_6F_5, CN, 4-CIC_6H_40(or C_6H_5O) ~1J_(CP)increasing→ The chemical shifts of the phosphorus have been found to be influenced by the nature of the substituents directly attached to the ylidio carbon but with different order: CN, P(O)(OC_6H_5)_2,C_6F_5,α-C_4H_3S,4ClC_6H_4O(or C_6H_5O), H(or COSCH_3),CHO chemical shifts toward upfield→