Carbon- and Sulfur-Bridged Diiron Carbonyl Complexes Containing N,C,S-Tridentate Ligands Derived from Functionalized Dibenzothiophenes: Mimics of the [FeFe]-Hydrogenase Active Site
Carbon- and Sulfur-Bridged Diiron Carbonyl Complexes Containing N,C,S-Tridentate Ligands Derived from Functionalized Dibenzothiophenes: Mimics of the [FeFe]-Hydrogenase Active Site
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DOI：
10.1021/om300826y
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发表时间：
2012-11-12
期刊：
影响因子：
2.8
通讯作者：
Kinoshita, Isamu
中科院分区：
文献类型：
--
作者：
Hirotsu, Masakazu;Santo, Kiyokazu;Kinoshita, Isamu
[Fe(CO)(5)]与含有N给基的二苯并噻吩（DBT）衍生物的光化学反应产生了一系列C，S桥接的二铁羰基配合物[{Fe(μ -L'-kappa N-3，C，S)(CO)(2)}Fe(CO)(3)]，如先前报道的4-（2'-吡啶基）二苯并噻吩(L-1'-L-5‘，其中L’代表N，C，S三齿配体L-1'-L-5'，分别由L-1-L-5的C-S键裂解形成。本研究中使用的DBT衍生物在4位上含有希夫碱或恶唑啉基团：L-2 = PhCH2N=CH-DBT, L-3 = 2-MeOC6H4CH2N=CH-DBT, L-4 = (S)-PhC(Me)HN=CH-DBT, L-5 = (R)-4-异丙基-2-恶唑啉-DBT。通过核磁共振、吸收光谱和圆二色光谱对二铁配合物进行了表征，并通过x射线晶体学建立了硫代S和芳基C原子桥接的双核结构。diiron复杂[{Fe(μL ' kappa n - 3 C S) (CO) (2)} Fe(有限公司)(3)]包含两个单位,Fe (L)(有限公司)(2)和铁(CO)(3):后者单元位于thiolate-containing metallacycle前手性席夫碱配体的前体骶给争取两个非对映体的混合物({Fe (mu-L-4 kappa n - 3 C S) (CO) (2)} Fe (CO)(3)],而手性与置之不理(R) 4-isopropyl-2-oxazolinyl集团提供[(Fe (mu-L-5 kappa n - 3 C年代)(CO) (2)} Fe(有限公司)(3)]在9:1非对映的比率。N，C， s三齿配体的二铁羰基配合物（L-1′- l -5′）对[Fe-2（mu-L′）（CO）(5)]（0/-）和[Fe-2(mu-L′（CO）(5)]（-/2-）表现出两种可逆的氧化还原偶。双电子还原形式进行质子化，并作为电催化剂醋酸在乙腈中的质子还原。
Photochemical reactions of [Fe(CO)(5)] with dibenzothiophene (DBT) derivatives bearing a N-donor group produced a series of C,S-bridged diiron carbonyl complexes [{Fe(mu-L'-kappa N-3,C,S)(CO)(2)}Fe(CO)(3)], as previously, reported for 4-(2'-pyridyl)dibenzothiophene (L-1'-L-5', where L' represents the N,C,S-tridentate ligands L-1'-L-5', formed by C-S bond cleavage of L-1-L-5, respectively. The DBT derivatives used in this study have Schiff base or oxazoline moieties at the 4-position: L-2 = PhCH2N=CH-DBT, L-3 = 2-MeOC6H4CH2N=CH-DBT, L-4 = (S)-PhC(Me)HN=CH-DBT, L-5 = (R)-4-isopropyl-2-oxazolinyl-DBT. The diiron complexes were characterized by NMR, absorption, and circular dichroism spectroscopy, and the dinuclear structures bridged by thiolate S and aryl C atoms were established by X-ray crystallography. The diiron complex [{Fe(mu-L'-kappa N-3,C,S)(CO)(2)}Fe(CO)(3)] consists of two units, Fe(L')(CO)(2) and Fe(CO)(3): the latter unit is located on a thiolate-containing metallacycle in the former one The chiral Schiff base ligand precursor L-4 gave a 55:45 mixture of two diastereomers for [{Fe(mu-L-4'-kappa N-3,C,S)(CO)(2)}Fe(CO)(3)], while chiral L-5 with an (R)-4-isopropyL-2-oxazolinyl group afforded [(Fe(mu-L-5'-kappa N-3,C,S)(CO)(2)}Fe(CO)(3)] in a 9:1 diastereomeric ratio. The diiron carbonyl complexes of the N,C,S-tridentate ligands (L-1'-L-5') showed two reversible redox couples for [Fe-2(mu-L')(CO)(5)](0/-) and [Fe-2(mu-L'(CO)(5)](-/2-). The two-electron-reduced forms undergo protonation and act as electrocatalysts for proton reduction of acetic acid in acetonitrile.