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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Topological Characterization of Three-Electron-Bonded Radical Anions
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Topological Characterization of Three-Electron-Bonded Radical Anions

机译：三电子键自由基阴离子的拓扑表征

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摘要

The three-electron bond in radical anions of the H_nXYH_m~- type, with X, Y = Cl, S, P, Si, F, O, N, C and n, m = 0 - 2, has been investigated from the topological analysis of the electron localization function (ELF) at the BH&HLYP level. It is shown that the topological modifications arising within the bonding region upon vertical electron attachment are of three different types, according to the vertical electron affinity (vEA) of the neutral compound: for vEA smaller than -16 kcal mol~(-1) the bonding population remains unchanged, as in H_4P_2, for negative vEA greater than -16 kcal mol~(-1) the bonding population decreases, as in H_2S_2 and for positive vEA the bonding population disappears, as in Cl_2. However, after relaxation of the geometry, the formation of the three-electron bond is accompanied in all cases by the disappearance of the X-Y bonding basin (which is the signature of the covalent bond in the neutral parent molecule). From a quantitative point of view, the topological approach also allows us to characterize the transfer of charge and spin densities that arises upon these processes toward the lone pairs basins of the X and Y atoms. Finally, to quantify the electron fluctuation between the two moieties, an index of delocalization has been defined from the analysis of the variance of the lone pairs population. This index increases approximately linearly with the dissociation energy D_e of the radical anions, provided that they are separated into a group of weakly bonded ones (D_e < 18 kcal mol~(-1)) and a group of strongly 3e-bonded ones (D_3 > 18 kcal mol~(-1)).
机译：从拓扑学上研究了H_nXYH_m〜-型自由基阴离子中的三电子键，其中X，Y = Cl，S，P，Si，F，O，N，C和n，m = 0-2。 BH＆HLYP级别的电子定位函数（ELF）的分析。结果表明，根据中性化合物的垂直电子亲和力（vEA），垂直电子附着后在键合区域内产生的拓扑结构变化可分为三种类型：对于小于-16 kcal mol〜（-1）的vEA，与H_4P_2一样，键合数量保持不变，对于大于-16 kcal mol〜（-1）的负vEA，键合数量减少，如在H_2S_2中;对于正vEA，键合数量消失，如Cl_2。但是，在几何形状放宽之后，在所有情况下三电子键的形成都伴随着X-Y键池的消失（这是中性母体分子中共价键的特征）。从定量的角度来看，拓扑方法还使我们能够表征在这些过程中产生的电荷和自旋密度向X和Y原子孤对池的转移。最后，为了量化两个部分之间的电子涨落，已通过对孤对种群的方差分析定义了离域指数。该指数随自由基阴离子的解离能D_e近似线性增加，前提是它们被分为一组弱键合的离子（D_e <18 kcal mol〜（-1））和一组强键合的3e键合的离子（D_3 > 18 kcal mol〜（-1））。

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