π-Lithium Noncovalent Interaction between π-Bond-Containing Compounds and NH2Li: A way of Construction for Supramolecular Materials

Abstract

In this paper, we optimized the geometries the π-lithium bond complexes between three π-bond-containing compounds, ethylene, acetylene, benzene, and amido-lithium have been calculated at DFT-D3/6-311++G**, MP2/6-311++G** and QCISD/6-311++G** theoretical levels. All the equilibrium geometries were confirmed to be stable state by analytical frequency computations. The calculations showed that all the bond lengths of the electron acceptors increased obviously and the red shift of N-Li stretching frequency occurred after complexes formed. The calculated binding energies, ΔEtot, of the four complexes are-38.11, -41.05 and-45.02 kJ·mol-1via the DFT-D3 method, respectively. Natural bond orbital theory analysis revealed that the three complexes were all formed with π-s type lithium bond interaction between three π-lithium bond donor molecules.