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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Stabilization of Saturated Carbocations in Condensed Phases
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Stabilization of Saturated Carbocations in Condensed Phases

机译：凝聚阶段饱和碳酸盐的稳定性

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摘要

Based on the experimentally established mechanism of hyperconjugative stabilization of the simplest saturated carbocations [Stoyanov, E. S.; et al. PCCP, 2017, 19, 7270], the infrared spectra of t-alkyl(+) and methyl-cyc/o-pentyr carbocations were interpreted. This approach allows us to extract new information about the electronic state of (CH3)(2)C+R cations with R = H, CH3, C2H5, C4H7, and CH(CH3)(2), namely, the electron density distribution over the (CH3)(2)C group and the positive charge dispersion on the H atoms of this group. Thus, donation of the electron density to the empty 2p(z) orbital of the sp(2) C atom occurs not only from one C-H bond oriented parallel to the 2p(z) orbital but also equally from all other C-H and C-C bonds of the molecular group involved in hyperconjugation. This mechanism preserved the isoelectronic nature of this group toward the corresponding groups of the neutral alkanes. Hyperconjugation and polarization are closely linked in stabilization of carbocations: the strengthening of one effect weakens the second and vice versa without changing the efficiency of 'scattering of the positive charge in the carbocation. In the condensed phase, carbocations are additionally stabilized by the bulk effect and hydrogen bonding with the environment: increasing H-bonding strength increased hyperconjugation and decreased polarization. The contribution of all the effects on the stabilization of carbocations was evaluated.
机译：基于实验建立的最简单饱和碳酸血管稳定化机制[STOYANOV，E.S;等等。 PCCP，2017,19,7270]，解释了T-烷基（+）和甲基-CYC / O-戊烷基碳的红外光谱。这种方法允许我们利用R = H，CH3，C2H5，C4H7和CH（CH3）（2）提取有关（CH3）（2）C + R阳离子的电子状态的新信息，即电子密度分布（CH3）（2）C组和该组H原子上的正电荷分散。因此，捐赠给SP（2）C原子的空2P（z）轨道的电子密度不仅从平行于2p（z）轨道的一个Ch键，而且来自所有其他CH和CC键分子组涉及超强凝固。该机制将该基团的异形性质朝向相应的中性烷烃组。超强谐波和极化在碳酸稳定中紧密相关：一项效果的强化削弱了第二个，反之亦然，而不会改变曲面中正电荷的散射效率。在冷凝阶段，通过散装效应和与环境氢键合另外稳定碳酸酯：增加H键合强度增加高速谐波和偏振降低。评估了所有对碳酸稳定的所有作用的贡献。

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