title: DFT/TDDFT study of lanthanide(III) mono- and bisporphyrin complexes.
abstract: The electronic structure, molecular structure, and electronic spectra of lanthanide(III) mono- and bisporphyrin complexes are investigated using a DFT/TDDFT method. These complexes include YbP(acac), YbP(2), [YbP(2)](+), YbHP(2), and [YbP(2)](-) (where P = porphine and acac = acetylacetonate). To shed some light on the origin of the out-of-plane displacement of Yb in YbP(acac), unligated model systems, namely, planar D(4h) and distorted C(4nu) YbP, were calculated. For comparison, the calculations were also extended to include the C and [Ce(IV)P(2) ](+) systems. Even without an axial ligand, the lanthanide atom lies considerably above the porphyrin plane; the distortion of the YbP molecular structure from a planar D(4h) to the nonplanar C(4nu) symmetry leads to a considerable energy lowering. The axial ligand makes the metal out-of-plane displacement even larger, and it also changes the redox properties of the lanthanide monoporphyrin. The ground-state configurations of YbP(2) and YbHP(2) were determined by considering several possible low-lying states. YbP(2) is confirmed to be a single-hole radical. The special redox properties of the bisporphyrin complexes can well be accounted for by the calculated ionization potentials and electron affinities. The TDDFT results provide a clear description of the UV-vis and near-IR absorption spectra of the various lanthanide porphyrins.
authors.affiliation: Department of Chemistry, P. O. Box 17910, Jackson State University, Jackson, Mississippi 39217, USA.
authors.forename: Meng-Sheng
authors.initials: MS
authors.lastname: Liao
authors.forename: John D
authors.initials: JD
authors.lastname: Watts
authors.forename: Ming-Ju
authors.initials: MJ
authors.lastname: Huang
mesh_terms: D002563:Cerium / Q000737:chemistry*; D004583:Electrons; D008958:Models, Molecular; D015394:Molecular Structure; D011166:Porphyrins / Q000737:chemistry*; D015018:Ytterbium / Q000737:chemistry*
chemical_list: D011166:Porphyrins; D002563:Cerium; D015018:Ytterbium