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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >π-Delocalization in Oligoalkynes Induced by Push-Pull Substituents and 1,3-Conjugation:A Combined ~(13)CNMR and Computational Study
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π-Delocalization in Oligoalkynes Induced by Push-Pull Substituents and 1,3-Conjugation:A Combined ~(13)CNMR and Computational Study

机译：推挽取代基和1,3-共轭作用引起的低炔烃中的π-离域：〜（13）CNMR和计算研究的组合

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摘要

13C chemical shifts of the push-pull oligoalkynes Don-(C=C)_n-Acc (n = 1-4; Don = morpholino; Acc =COMe, COOMe) were computed at the DFT (B3LYP/6-311+G(d,p) level of theory compared with theexperimental 6 values and the agreement employed as a measure of quality for the underlying structures. Forthe global minima structures, the occupation quotients of antibonding π* and bonding π orbitals (π~*-dgrcc) and the bond lengths (cle) of the various C=C triple bonds were also computed and correlated toeach other. The linear dependence obtained for the two parametersandccoc quantifies changesin π-delocalization induced by the push-pull effect of the substituents and 1,3-conjugation (1,3,5- and 1,3,5,7-,respectively) of the C=C bonds in the oligoalkynes studied. A critical comparison of the push-pull effect,attenuated with increasing n, and the conjugative stabilization of the oligoalkynes, increasing with n, asconcluded from c/c.c and π*c--/2re c of the oligoalkynes and the reference compounds Me-(C)_n-Me,Don-(C--C)_n-Me, and Me-(C-=-C)_n-Acc), respectively (Don = morpholino; Acc = COMe, COOMe), isaffiliated.
机译：推挽式低聚炔Don-（C = C）_n-Acc（n = 1-4; Don =吗啉代; Acc = COMe，COOMe）的13C化学位移在DFT（B3LYP / 6-311 + G（ d，p）的理论水平与实验6值和用于衡量基础结构质量的协议的比较。对于全局最小结构，反键π*和键π轨道（π〜* -dgrcc）和还计算了各个C = C三键的键长（cle）并将它们相互关联。对于两个参数andc / ncoc所获得的线性依赖性可量化由取代基和1的推挽效应引起的π离域变化研究了低炔烃中C = C键的3个共轭（分别为1,3,5-和1,3,5,7-）。推挽效应的临界比较，随着n的增加而衰减，并且寡炔和参考化合物的c / cc和π* c-/ 2re c得出结论，低炔烃的共轭稳定随着n的增加而增加。 ds Me-（C）_n-Me，Don-（CC）_n-Me和Me-（C-=-C）_n-Acc）（Don =吗啉代; Acc = COMe，COOMe）。

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