Hocking Rosalie K, Wasinger Erik C, de Groot Frank M F, Hodgson Keith O, Hedman Britt, Solomon Edward I
Department of Chemistry, Stanford University, Stanford, California 94305, USA.
J Am Chem Soc. 2006 Aug 16;128(32):10442-51. doi: 10.1021/ja061802i.
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.
已识别出两种化合物K3[Fe(CN)6]和K4[Fe(CN)6]在铁L边的独特光谱特征，并将其表征为由于金属到配体的反馈键合导致的配体π轨道贡献。此外，L边能量位移和总强度可以确定配体场和有效核电荷的变化。发现配体场项主导了边能量位移。将实验分析结果与BP86密度泛函理论（DFT）计算进行了比较。计算结果与实验总体吻合良好；然而，实验发现Fe(II)和Fe(III)之间的π反馈量存在较大差异。对L边光谱形状、能量位移和总强度的分析表明，铁L边X射线吸收光谱提供了对金属到配体反馈键合的直接探测。
