具有共轭结构单元的有机二硫化物双硫键的结构及其电子性质的理论研究

Theoretical Study on Structures and Electronic Properties of Disulfide Bonds in Organic Disulfides with Conjugated Configurations

在AUG-cc-pVDZ基组水平上,通过B3LYP密度泛函方法计算,预测了4类有机二硫化物体系的结构、电子亲合能、电离能及结构修饰对其性质的影响.计算表明,有机共轭硫化物中的S—S键具有良好的过剩电子储存能力,过剩电子进入σ*S—S反键轨道,可以形成稳定的两中心三电子双硫键([S∴S]-).强吸电子基团—NO2的存在对低能空轨道能级有一定的影响,但σ*S—S反键轨道在大多数情况下都是储存过剩电子的低能前线轨道.这种特殊的三电子双硫键性质及其结构修饰效应,对提升有机二硫化物体系作为电池正极材料的性能具有重要意义.

Equilibrium geometries, electron affinities, ionization potentials, and effects of structural modification on their properties of selected organic disulfides have been investigated by B3LYP/AUG-cc-pVDZ calculations.The present results show that the S S bond of these disulfides can accommodate the excess electron effectively via the σs-s antibonding orbital and form a stable two center three-electron （2c-3e） [S∴ S]- bond.The presence of strong electron-withdrawing group --NO2 can slightly change the energy order of frontier orbitals to some extent, but the σs-s is still the lower-energy unoccupied frontier orbital for the storage of excess electrons. Such disulfide bonding features are helpful for the performance improvement of organic disulfides as the cathode materials of battery.