Density functional theory studies of lithium porphyrin radicals

• DOI: 10.1016/j.chemphys.2004.06.044
• Publication Date: 2004-07-27T21:39:35Z
• Authors: Xu Lian-Cai; Li Zun-Yun; He Tian-Jing; Liu Fan-Chen; Chen Dong-Ming
• Keywords: 01 natural sciences; 0104 chemical sciences

Abstract The ground-state geometries of monolithium porphyrin (LiP) π-radical and its three reduced/oxidized species ([LiP] − , [LiP] 2− , and [LiP] + ) have been calculated with the density functional theory. The results show that LiP, [LiP] − and [LiP] + have planar D 4h structures while the [LiP] 2− dianion has a rectangular distorted D 2h structure due to the ground-state Jahn-Teller effect. LiTPP and LiOEP radicals were also studied to assess the effect of peripheral substitutions. The ground-state LiTPP has a normal porphyrin ring (D 4h effective symmetry), while the ground-state LiOEP has a porphyrin ring with pronounced bond length alternation (C 4h effective symmetry) due to the pseudo-Jahn-Teller (pJT) distortion along an A 2g -like coordinate. The spin densities of LiP, LiTPP, and LiOEP were analyzed, showing evident effects of peripheral substitution. Electronic absorption spectrum of LiP radical was calculated with the time-dependent DFT and was compared with the experimental results of LiTPP.