title: Fe L-edge XAS studies of K4[Fe(CN)6] and K3[Fe(CN)6]: a direct probe of back-bonding.
abstract: Distinct spectral features at the Fe L-edge of the two compounds K3[Fe(CN)6] and K4[Fe(CN)6] have been identified and characterized as arising from contributions of the ligand pi orbitals due to metal-to-ligand back-bonding. In addition, the L-edge energy shifts and total intensities allow changes in the ligand field and effective nuclear charge to be determined. It is found that the ligand field term dominates the edge energy shift. The results of the experimental analysis were compared to BP86 DFT calculations. The overall agreement between the calculations and experiment is good; however, a larger difference in the amount of pi back-donation between Fe(II) and Fe(III) is found experimentally. The analysis of L-edge spectral shape, energy shift, and total intensity demonstrates that Fe L-edge X-ray absorption spectroscopy provides a direct probe of metal-to-ligand back-bonding.
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California 94305, USA.
authors.forename: Rosalie K
authors.initials: RK
authors.lastname: Hocking
authors.forename: Erik C
authors.initials: EC
authors.lastname: Wasinger
authors.forename: Frank M F
authors.initials: FM
authors.lastname: de Groot
authors.forename: Keith O
authors.initials: KO
authors.lastname: Hodgson
authors.forename: Britt
authors.initials: B
authors.lastname: Hedman
authors.forename: Edward I
authors.initials: EI
authors.lastname: Solomon
mesh_terms: D000465:Algorithms; D005292:Ferricyanides / Q000737:chemistry*; D008024:Ligands; D011188:Potassium / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods; D014965:X-Rays
chemical_list: D005292:Ferricyanides; D008024:Ligands; C007931:hexacyanoferrate III; D011188:Potassium; C028033:potassium ferricyanide