Laboratory of Quantum Chemistry Department of Theoretical Chemistry Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland.
Chempluschem. 2020 Feb;85(2):312-318. doi: 10.1002/cplu.202000007.
Theoretical investigation of the H(CHB X ) (X=H, F, Cl, CN), H(CHB X Y ) (X,Y=F, Cl; n=1,5), and dimeric (H(CHB X )) (X=F, Cl) carborane superacids performed at the B3LYP/6-311++G(d,p) theory level revealed the similarity of their equilibrium structures and the possibility of nearly barrierless hydrogen atom migration among the substituents attached to one side of the icosahedral CB cage. The vertical electron detachment energies predicted at the OVGF/6-311++G(3df,2pd) theory level for the conjugate bases (CHB X ) were found to span the 5.82-9.00 ev range. The acid strengths (manifested by the Gibbs free deprotonation energies spanning the 213-266 kcal/mol range) predicted for the icosahedral H(CHB X ) carborane systems confirm their superacidic properties which might be increased even further by the attachment of the second carborane H(CHB X ) unit that leads to a dimeric structure mimicking a part of an experimentally observed H-bridged polymeric chain. The Gibbs free deprotonation energy of the dimeric (H(CHB Cl )) acid was predicted to be smaller by 17 kcal/mol than that of the corresponding monomeric H(CHB Cl ) acid.
采用 B3LYP/6-311++G(d,p)理论水平对 H(CHB X )(X=H、F、Cl、CN)、H(CHB X Y )(X、Y=F、Cl;n=1、5)和二聚体(H(CHB X ))(X=F、Cl)碳硼烷超酸进行了理论研究，结果表明它们的平衡结构具有相似性，并且在五配位笼一侧连接的取代基之间可能存在近乎无势垒的氢原子迁移。在 OVGF/6-311++G(3df,2pd)理论水平预测的共轭碱(CHB X )的垂直电子离解能被发现跨越 5.82-9.00 eV 的范围。预测的二十面体 H(CHB X )碳硼烷体系的酸度(由跨越 213-266 kcal/mol 范围的吉布斯自由质子化能体现)证实了它们的超酸性，通过附加第二个碳硼烷 H(CHB X )单元可以进一步提高其酸度，从而形成类似于实验观察到的 H 桥接聚合物链的一部分的二聚体结构。预测二聚体(H(CHB Cl ))酸的吉布斯自由质子化能比相应的单体 H(CHB Cl )酸小 17 kcal/mol。
