Bridging-hydride influence on the electronic structure of an [FeFe] hydrogenase active-site model complex revealed by XAES-DFT
學年 101
學期 2
出版（發表）日期 2013-06-07
作品名稱 Bridging-hydride influence on the electronic structure of an [FeFe] hydrogenase active-site model complex revealed by XAES-DFT
作品名稱（其他語言）
著者 Leidel, Nils; Hsieh, Chung-Hung; Chernev, Petko; Sigfridsson, Kajsa G. V.; Darensbourg, Marcetta Y.; Haumann, Michael
單位 淡江大學化學學系
出版者 Cambridge: R S C Publications
著錄名稱、卷期、頁數 Dalton Transactions 42(21), pp.7539-7554
摘要 Two crystallized [FeFe] hydrogenase model complexes, 1 = (μ-pdt)[Fe(CO)2(PMe3)]2 (pdt = SC1H2C2H2C3H2S), and their bridging-hydride (Hy) derivative, [1Hy]+++ = [(μ-H)(μ-pdt)[Fe(CO)2 (PMe3)]2]+ (BF4−), were studied by Fe K-edge X-ray absorption and emission spectroscopy, supported by density functional theory. Structural changes in [1Hy]+++ compared to 1 involved small bond elongations (<0.03 Å) and more octahedral Fe geometries; the Fe–H bond at Fe1 (closer to pdt-C2) was [similar]0.03 Å longer than that at Fe2. Analyses of (1) pre-edge absorption spectra (core-to-valence transitions), (2) Kβ1,3, Kβ′, and Kβ2,5 emission spectra (valence-to-core transitions), and (3) resonant inelastic X-ray scattering data (valence-to-valence transitions) for resonant and non-resonant excitation and respective spectral simulations indicated the following: (1) the mean Fe oxidation state was similar in both complexes, due to electron density transfer from the ligands to Hy in [1Hy]+++. Fe 1s→3d transitions remained at similar energies whereas delocalization of carbonyl AOs onto Fe and significant Hy-contributions to MOs caused an [similar]0.7 eV up-shift of Fe1s→(CO)s,p transitions in [1Hy]+++. Fed-levels were delocalized over Fe1 and Fe2 and degeneracies biased to Oh–Fe1 and C4v–Fe2 states for 1, but to Oh–Fe1,2 states for [1Hy]+++. (2) Electron-pairing of formal Fe(d7) ions in low-spin states in both complexes and a higher effective spin count for [1Hy]+++ were suggested by comparison with iron reference compounds. Electronic decays from Fe d and ligand s,p MOs and spectral contributions from Hys,p→1s transitions even revealed limited site-selectivity for detection of Fe1 or Fe2 in [1Hy]+++. The HOMO/LUMO energy gap for 1 was estimated as 3.0 ± 0.5 eV. (3) For [1Hy]+++ compared to 1, increased Fed (x2 − y2) − (z2) energy differences ([similar]0.5 eV to [similar]0.9 eV) and Fed→d transition energies ([similar]2.9 eV to [similar]3.7 eV) were assigned. These results reveal the specific impact of Hy-binding on the electronic structure of diiron compounds and provide guidelines for a directed search of hydride species in hydrogenases.
關鍵字
語言 en
ISSN 1477-9234
期刊性質 國外
收錄於 SCI
產學合作
通訊作者
審稿制度 是
國別 GBR
公開徵稿
出版型式 ,電子版,紙本
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