Density functional theory investigations of geometries and electronic spectra of lithium phthalocyanines

The ground-state geometries of dilithium and monolithium complexes of phthalocyanine (Li2Pc and LiPc) and three reduced/oxidized species of LiPc (i.e., [LiPc]−, [LiPc]2− and [LiPc]+) have been studied with the density functional theory. It was shown that Li2Pc has a stable D4h structure with the two lithium atoms bonded symmetrically up and below the Pc plane. Both LiPc and [LiPc]− have a planar D4h structure whereas [LiPc]+ has a significantly saddle-distorted D2d structure. [LiPc]2− has a planar D2h structure with a rectangular distortion due to the ground state Jahn–Teller effect. Electronic absorption spectra of Li2Pc and LiPc were calculated with the time-dependent DFT method, and the results are in good agreement with the experiments.