HB=BH与离子-π作用的B3LYP和MP2(full)研究

摘要

采用B3LYP和MP2 (full)的方法,研究了缺电子B=B双键与离子(H+,Li+,Na+,Be2+和Mg2+)形成的复合物离子-π作用的特性. 分子间相互作用能由大到小的顺序为 HB=BH…H+,HB=BH… Be2+,HB=BH… Mg2+,HB=BH…Li+,HB=BH…Na+.HB=BH(1△μ)与离子间相互作用能比HC=CH与相应离子间的相互作用能强.利用自然键轨道(NBO)的分析,原子在分子中(AIM)理论及电子云密度转移方法揭示了离子-π作用的本质. B=B的π轨道的电子云转移到金属离子,形成离子-π作用.HB=BH… H+复合物呈现一定的共价性.%The nature of unusual cation-π interaction was investigated by carrying out B3LYP and MP2 (full) theoretical calculations ot the complexes of cations (H- , Li+, Na+,Be21 and Mg7+) with the electron-deficient B=B double bond. The interaction energies were calculated using MP2(full) and B3LYP methods at 6-311 ++G(2df ,2p) and aug-cc-pVTZ levels, and the value from big to small was : HB=BH…H-, HB=BH…Be2+ , HB=BH…Mg2+ , HB=BH…Li+, HB=BH…Na-. Furthermore, the interaction energies between HB=BH ('A,.) snd cations are stronger than iKose of he HC = CH complexes wilh the corresponding cations. The analyses of natural bond orbital (NBO). atoms in molecules (AIM) theory and electron density shifts reveal that the origin of the cation-Ti interaction is that many of the lost densities from the π-orbital of B=B are shifted toward the cation, leading to the electron densities accumulation and the formation of the cation-π interaction. Differently from the other complexes ， the complex of H- is indicative of covalent interaction.