4,5—二氧—2—硫—1,3,2,4—二氮二磷杂环戊烷衍生物的^(31)P NMR谱

THE ~ (31)P NMR SPECTRA OF 4,5 - DIOXO - 2 - THIO -1,3,2,4 -DIAZADIPHOSPHOLANE DERIVATIVES

^(31)PNMR谱表明,在4,5-二氧-2-硫-1,3,2,4-二氮二磷杂环戊烷类型化合物中,存在着顺式和反式两种异构体.顺式异构体化学位移出现在高场,~2J_(pp)偶全合常数较大;而反式异构体化学位移在低场,~2J_(pp)偶合常数较小.用Van der Waals排斥力和Pπ-dπ反馈理论解释了以上现象,并讨论了其他取代基R、X对^(31)P—NMR化学位移的影响.

It was found from the 31P NMR spectra that there were cis-and trans isomers in 4,5-dioxo-2-thio-1,3,2,4-diazadiphospholanes. The chemical shifts of the cis-isomer appeared at highfield with larger 2JPP coupling constant and the trans-isomer at lowficld with smaller coupling constant. It was explained in terms of van der Waals action and conjugated( P→d) π system. The relationship between the 31P NMR chemical shifts and substituent in phenyl is also discussed.