Theoretical observations of the single-electron lithium system H-Be⋯Li-Y (Y = H, OH, F, CCH, CN and NC)

A theoretical calculation of MP2/6-311++G** and MP2/aug-cc-pVDZ was used to predict the single-electron lithium bond system of H-Be⋯Li-Y (Y = H, OH, F, CCH, CN and NC). The results confirmed H-Be and Li-Y could interact to form the complexes I (HBe⋯Li-H), II (HBe⋯Li-OH), III (HBe⋯Li-F), IV (HBe⋯Li-CCH), V (HBe⋯Li-CN), and VI (HBe⋯Li-NC). The binding energies for these complexes ranged from −22.06 to −27.69 kJ mol−1 at the CCSD(T)/aug-cc-pVDZ//MP2/aug-cc-pVDZ level. Complex strength was in the order I < II < III < IV < V < VI. Analysis of the stretching frequencies showed that complexes I-III were red-shifting single-electron lithium bonds complexes. In contrast, complexes IV-VI were abnormal blue-shifting complexes, and the Li-Y bonds were longer in the complexes than in the corresponding monomers. The characteristics of the complexes were investigated using natural bond orbital (NBO), atoms-in-molecules (AIM) and electrostatic potential map (EPM) theories.