Dataset Information


Iron L-edge X-ray absorption spectroscopy of oxy-picket fence porphyrin: experimental insight into Fe-O2 bonding.

ABSTRACT: The electronic structure of the Fe-O(2) center in oxy-hemoglobin and oxy-myoglobin is a long-standing issue in the field of bioinorganic chemistry. Spectroscopic studies have been complicated by the highly delocalized nature of the porphyrin, and calculations require interpretation of multideterminant wave functions for a highly covalent metal site. Here, iron L-edge X-ray absorption spectroscopy, interpreted using a valence bond configuration interaction multiplet model, is applied to directly probe the electronic structure of the iron in the biomimetic Fe-O(2) heme complex [Fe(pfp)(1-MeIm)O(2)] (pfp ("picket fence porphyrin") = meso-tetra(?,?,?,?-o-pivalamidophenyl)porphyrin or TpivPP). This method allows separate estimates of ?-donor, ?-donor, and ?-acceptor interactions through ligand-to-metal charge transfer and metal-to-ligand charge transfer mixing pathways. The L-edge spectrum of [Fe(pfp)(1-MeIm)O(2)] is further compared to those of [Fe(II)(pfp)(1-MeIm)(2)], [Fe(II)(pfp)], and [Fe(III)(tpp)(ImH)(2)]Cl (tpp = meso-tetraphenylporphyrin) which have Fe(II)S = 0, Fe(II)S = 1, and Fe(III)S = 1/2 ground states, respectively. These serve as references for the three possible contributions to the ground state of oxy-pfp. The Fe-O(2) pfp site is experimentally determined to have both significant ?-donation and a strong ?-interaction of the O(2) with the iron, with the latter having implications with respect to the spin polarization of the ground state.

PROVIDER: S-EPMC3614349 | BioStudies |

REPOSITORIES: biostudies

Similar Datasets

| S-EPMC6386657 | BioStudies
| S-EPMC2964071 | BioStudies
| S-EPMC2630385 | BioStudies
| S-EPMC2515358 | BioStudies
| S-EPMC8433652 | BioStudies
| S-EPMC1502376 | BioStudies
| S-EPMC4999340 | BioStudies
2014-01-01 | S-EPMC6271358 | BioStudies
| S-EPMC3915880 | BioStudies
| S-EPMC3009112 | BioStudies