X-ray absorption spectroscopy and density functional theory studies of [(H3buea)FeIII-X]n- (X = S2-, O2-, OH-):: Comparison of bonding and hydrogen bonding in oxo and sulfido complexes
X-ray absorption spectroscopy and density functional theory studies of [(H3buea)FeIII-X]n- (X = S2-, O2-, OH-):: Comparison of bonding and hydrogen bonding in oxo and sulfido complexes
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DOI：
10.1021/ja061618x
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发表时间：
2006-08-02
影响因子：
15
通讯作者：
Solomon, Edward I.
中科院分区：
文献类型：
--
作者：
Dey, Abhishek;Hocking, Rosalie K.;Solomon, Edward I.
对一系列化合物[Fe（III）H（3）buea（X）]（n-）（X = S2-、O2-、OH-）进行了铁L边、铁K边和硫K边X射线吸收光谱。实验确定的电子结构被用来关联到密度泛函理论计算。然后使用数据支持的计算来比较金属-配体键合，并评估Fe-III-O与Fe-III-S络合物中H-键合的影响。发现Fe-III-O键虽然共价性较低，但比Fe-III-S键强。这主要反映了较大的离子贡献的Fe-III-O键。与硫化物配体的-12 kcal/mol相比，氧代的H-键合能\（对于三个H-键）估计为-25 kcal/mol。这种差异归因于由Fe-O键的较低共价性导致的氧代配体上的较大电荷密度。这些结果被扩展到考虑具有相同配体环境的Fe-IV-O络合物。结果表明，Fe-IV-O键的氢键比Fe-III-O键的氢键在能量上更弱，这反映了Fe-IV-O键的高度共价性。
Iron L-edge, iron K-edge, and sulfur K-edge X-ray absorption spectroscopy was performed on a series of compounds [Fe(III)H(3)buea(X)](n-) (X = S2-, O2-, OH-). The experimentally determined electronic structures were used to correlate to density functional theory calculations. Calculations supported by the data were then used to compare the metal-ligand bonding and to evaluate the effects of H-bonding in Fe-III-O vs Fe-III-S complexes. It was found that the Fe-III-O bond, while less covalent, is stronger than the Fe-III-S bond. This dominantly reflects the larger ionic contribution to the Fe-III-O bond. The H-bonding energy\ (for three H-bonds) was estimated to be -25 kcal/mol for the oxo as compared to -12 kcal/mol for the sulfide ligand. This difference is attributed to the larger charge density on the oxo ligand resulting from the lower covalency of the Fe-O bond. These results were extended to consider an Fe-IV-O complex with the same ligand environment. It was found that hydrogen bonding to Fe-IV-O is less energetically favorable than that to Fe-III-O, which reflects the highly covalent nature of the Fe-IV-O bond.