HBBH与离子-π作用的B3LYP和MP2(full)研究

A B3LYP and MP2(full) Theoretical Investigation on Unusual Interaction Between HBBH and Cation-π

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(1Δg)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 of the complexes of cations(H+,Li+,Na+,Be2+ and Mg2+) with the electron-deficient BB 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 HBBH(1Δg) and cations are stronger than those of the HC≡CH complexes with 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-π 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.