DFT Study on Structural Distortion and Vibronic Coupling of Vanadyl Porphyrin Anion and Cation

Abstract

The geometries of one‐electron reduced/oxidized species ([TOP]−/[VOP]+) of vanadyl porphyrin (VOP) have been calculated with PBE1PBE method. The results show that for both [VOP]− and [VOP]+ the ground states are triplet, in which one of the two unpaired electron occupies the dxy orbital of the V atom while the other occupies the π‐orbital of porphyrin ring. Thus both [VOP]− and [VOP]+ can be considered as π‐radicals. The ground state of neutral VOP molecule is doublet with the unpaired electron occupying dxy orbital of V atom. In contract to the C4v symmetry of neutral VOP molecule, [VOP]− anion has a “rectangular” distorted C2v structure due to Jahn‐Teller effect. The linear vibronic coupling constants for the Jahn‐Teller active modes of [TOP]− were evaluated and the node patterns of frontier KS orbitals are used to explain the reason why the distortion occurs along specific modes. The ground state [VOP]+ has a porphyrin ring with pronounced bond length alternation due to pseudo‐Jahn‐Teller effect, causi...