A Theoretical Study on Geometries and Electronic Structures of ONNO-type Ligand as a New Lithium Transport

Abstract

We have been studying phenanthroline derivatives from the experimental and theoretical points of view. Recently, one of the authors (S. O.) reported that a new phenanthroline derivative featuring high selectivity for the lithium cation complexation as carriers was synthesized. The simplicity of this carrier 1 itself and highly efficient separation of LiCl from the mixture including various alkali metal chlorides would meet the practical uses. Since this molecule has the cavity ringed by oxygen and nitrogen atoms as a coordination site, this complexation to the lithium cation is new type of coordination. Calculations using ab initio restricted Hartree-Fock molecular orbital (RHF MO) theory with the 3-21G and 6-31G* basis sets are reported for phenanthroline derivatives as well as its lithium complexes. Force constant matrices were calculated at stationary points in order to identify them as minima. The optimized geometries are consistent with the structural formula expected from the experiment. Stoichiometry of the complex, complexation energies, and frontier orbitals are discussed.