A comparison of the one-dimensional band structures of Ni tetrabenzoporphyrin and phthalocyanine conducting polymers

The one-dimensional band structures of (tetrabenzoporphyrinato) Ni(II) and (phthalocyaninato) Ni(II) were calculated. The reported band structures include the effects of the stacking perturbation and of the overlap between nearest neighbors. The basis functions for the intermolecular integrals were obtained from a discrete variational X-α calculation of the monomelic species. Electron spin resonance (ESR) experiments on conductive columnar stacks of these metallomacrocycles, partially oxidized with iodine, indicate that carrier electrons are primarily localized onto the ligands in the phthalocyanine species, but also involve the metal in the tetrabenzoporphyrin complex. The present calculations suggest that the ESR data results from a band crossing or near degeneracy between the highest occupied (ligand centered) porphyrin molecular orbital, and the lowest occupied (metal centered) molecular orbital. The analogous levels are more separated in energy in the phthalocyanine derivative.