Density functional theory study on the dynamic Jahn-Teller effect of tetraoxaporphyrin cation and anion radicals

Abstract

The ground state geometries of tetraoxaporphyrin monocation/monoanion radicals (i.e., [TOP ] − and [TOP ] +) and their parent neutral molecule (TOP) have been studied with DFT at the B3LYP/6-31G(d) level of theory. It was shown that both [TOP ] − and [TOP ] + have planar D 2h structures with a rectangular distortion due to the Jahn-Teller (JT) effect. The two conjugated rectangular JT structures can inter-convert dynamically thought a rhombic transition state. The ESR isotropic hyperfine coupling constants on the H atoms ( a H) of the radicals were calculated and were found in good agreement with the experiments. The linear vibronic coupling constants were evaluated with DFT calculations, revealing that the B 1g modes corresponding to the stretches of the C α C m and C β C β bonds and the furan symmetric deformation play a critical role in the JT effect of [TOP ] − and [TOP ] +.