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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Experimental and Theoretical Study of Hyperconjugative Interaction Effects on NMR ~1J_(CH)Scalar Couplings
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Experimental and Theoretical Study of Hyperconjugative Interaction Effects on NMR ~1J_(CH)Scalar Couplings

机译：超共轭相互作用对NMR〜1J_（CH）标量耦合的实验和理论研究

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摘要

Hyperconjugative and electrostatic interactions effects on ~1J_(CH)spin-spin coupling constants(SSCCs)are critically studied from both theoretical and experimental points of view.A qualitative model is used to predict how the former affect such SSCCs,while electrostatic interactions are modeled with a point charge placed in the vicinity of the corresponding sigma_(CH)bond.Hyperconjugative interactions are calculated using the"natural bond orbital"approach,and using the point-charge model,it is shown how intertwined are both types of interactions.Several members of the series 1-X-bicyclo[1.1.1]pentane and 1-X-3-methylbicyclo[1.1.1]pentane are chosen as model compounds for measuring ~1J_(CH)SSCCs;in some of them were performed also DFT-SSCC calculations.The strained cage substrate in these series defines strong sigma-hyperconjugative interactions,making these compounds excellent examples to verify the qualitative model presented in this work.It is verified that(a)hyperconjugative interactions from the sigma_(CH)bond or into the sigma*CH antibond containing the coupling nuclei yield a decrease of the corresponding ~1J_(CH)SSCC and(b)hyperconjugative interactions from other bonds involving the coupling C nucleus yield an increase of that ~1J_(CH)SSCC.
机译：从理论和实验的角度对超共轭和静电相互作用对〜1J_（CH）自旋-自旋耦合常数（SSCC）的影响进行了严格研究。使用“自然键轨道”方法计算超共轭相互作用，并使用点电荷模型，计算出两种类型的相互作用是如何交织的。选择1-X-双环[1.1.1]戊烷系列和1-X-3-甲基双环[1.1.1]戊烷系列的成员作为测量〜1J_（CH）SSCC的模型化合物;其中一些还进行了DFT-SSCC计算。该系列中的应变笼式底物定义了强大的sigma-超共轭相互作用，使这些化合物成为验证本工作提出的定性模型的优秀实例。来自sigma_（CH）键或包含耦合原子核的sigma * CH反键的离子产生相应的〜1J_（CH）SSCC减少，并且（b）来自涉及键合C核的其他键的超共轭相互作用产生的增加〜1J_（CH）SSCC。

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