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首页> 外文期刊>Russian Journal of Inorganic Chemistry >Theoretical Study of Molecular Hydrogen Elimination from the Undecahydrodecaborate Monoanion [B_(10)H_(11)]~-.Exopolyhedral Substitution Intermediates: [B_(10)H_9]~- Monoanion and Neutral [B_(10)H_(10)] Cluster
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Theoretical Study of Molecular Hydrogen Elimination from the Undecahydrodecaborate Monoanion [B_(10)H_(11)]~-.Exopolyhedral Substitution Intermediates: [B_(10)H_9]~- Monoanion and Neutral [B_(10)H_(10)] Cluster

机译：十一氢脱氢单阴离子[B_（10）H_（11）]〜-。多面体取代中间体：[B_（10）H_9]〜-单阴离子和中性[B_（10）H_（10）]团簇消除分子氢的理论研究

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摘要

The elementary reaction of molecular hydrogen elimination from the [B_(10)H_(11)]~- anion, which is presumably the rate-limiting stage of acid-catalyzed reactions of substitution of exopolyhedral H atoms in the [B_(10)H_(10)]~(2-)_ decahydro-claso-decaborate anion, has been calculated by the density functional theory method (in the B3LYP/6-311++G** approximation). Specific transition states of H_2 elimination in which vacancies form near the boron atoms have been localized. It has been demonstrated that regioselectivity of substitution reactions can be related to the significant difference between the activation barriers for the pathways of H_2 elimination from boron atoms with different coordination numbers (CN 6 and 5). The electron density of the [B_(10)H_9]~ anion that forms after hydrogen molecule elimination has a characteristic shape of the lowest unoccupied molecular orbital for the interaction with nucleophilic reagents; in acid-catalyzed reactions, different anions, for example, a carboxylic acid residue, can act as such. The direct reaction of the [B_(10)H_9]~_ intermediate with nucleophilic anions is hindered by the Coulomb charge repulsion. To overcome this hindrance, the possibility of [B_(10)H_9]~ protonation to form the neutral [B_(10)H_(10)] system has been considered. It has been shown that the proton affinity of the [B_(10)H_9]~ anion is～-280-290 kcal/mol. For the [B_(10)H_(10)] cluster, the lowest-lying and low-lying isomers have been considered. For all the systems under consideration, the electronic chemical potential and Pearson hardness have been evaluated.
机译：从[B_（10）H_（11）]-阴离子中消除氢分子的基本反应，这可能是[B_（10）H_中酸的外多面体H原子取代的酸催化反应的限速阶段（10）]〜（2-）_十氢-claso脱氧阴离子，已通过密度泛函理论方法（以B3LYP / 6-311 ++ G **近似）计算。在硼原子附近形成空位的H_2消除的特定过渡态已经被定位。已经证明，取代反应的区域选择性可能与具有不同配位数（CN 6和5）的硼原子从氢原子消除H_2的途径的激活势垒之间的显着差异有关。氢分子消除后形成的[B_（10）H_9]〜阴离子的电子密度具有与亲核试剂相互作用的最低未占据分子轨道的特征形状。在酸催化的反应中，不同的阴离子（例如羧酸残基）可以这样起作用。库仑电荷排斥作用阻碍了[B_（10）H_9]〜中间体与亲核阴离子的直接反应。为了克服这一障碍，已经考虑了[B_（10）H_9]〜质子化形成中性[B_（10）H_（10）]系统的可能性。结果表明，[B_（10）H_9]〜阴离子的质子亲和力约为-280-290 kcal / mol。对于[B_（10）H_（10）]簇，已考虑了最低位和最低位的异构体。对于所有考虑中的系统，已经评估了电子化学势和皮尔逊硬度。

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