@article {ISI:A1997XJ83300011,
	title = {A Multiplet Analysis of Fe K-Edge 1s {\textrightarrow} 3d Pre-Edge Features of Iron Complexes},
	journal = {J. Am. Chem. Soc.},
	volume = {119},
	number = {27},
	year = {1997},
	month = {jul},
	pages = {6297{\textendash}6314},
	abstract = {X-ray absorption Fe-K edge data on ferrous and ferric model complexes have been studied to establish a detailed understanding of the 1s {\textendash}> 3d pre-edge feature and its sensitivity to the electronic structure of the iron site. The energy position and splitting, and intensity distribution, of the pre-edge feature were found to vary systematically with spin state, oxidation state, geometry, and bridging ligation (for binuclear complexes). A methodology for interpreting the energy splitting and intensity distribution of the 1s {\textendash}> 3d pre-edge features was developed for high-spin ferrous and ferric complexes in octahedral, tetrahedral, and square pyramidal environments and low-spin ferrous and ferric complexes in octahedral environments. In each case, the allowable many-electron excited states were determined using ligand field theory. The energies of the excited states were calculated and compared to the energy splitting in the 1s {\textendash}> 3d pre-edge features. The relative intensities of electric quadrupole transitions into the many-electron excited states were obtained and compared to the intensity pattern of the pre-edge feature. The effects of distorting the octahedral iron site to tetrahedral and square pyramidal geometries were analyzed. The contributions to the pre-edge intensity from both electric quadrupole and electric dipole (from 3d-4p mixing) intensity mechanisms were established for these distorted cases; the amount of 4p character and its distribution over the many-electron final states were experimentally estimated and compared to theoretical predictions from density functional calculations. The methodology was also applied to binuclear complexes, and a clear marker for the presence of a mu-oxo Fe-O-Fe bridge was established. General trends in 3d-4p mixing are developed and discussed for a series of geometries and oxidation states of Fe complexes. The results presented should further aid in the interpretation of the Is - 3d pre-edge region of iron complexes and non-heme iron enzymes.},
	keywords = {PhD},
	issn = {0002-7863},
	doi = {10.1021/ja964352a},
	url = {http://pubs.acs.org/doi/abs/10.1021/ja964352a},
	author = {Westre, Tami E and Kennepohl, Pierre and DeWitt, Jane G and Hedman, Britt and Hodgson, Keith O and Solomon, Edward I}
}
