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首页> 外文期刊>Catalysis science & technology >Hydroboration of terminal olefins with pinacolborane catalyzed by new 2-iminopyrrolyl iron(II) complexes
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Hydroboration of terminal olefins with pinacolborane catalyzed by new 2-iminopyrrolyl iron(II) complexes

机译：硼氢化反应的末端烯烃由新2-iminopyrrolyl pinacolborane催化铁(II)配合物

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摘要

Four paramagnetic 14-electron tetracoordinated Fe(II) complexes of 5-substituted-2-iminopyrrolyl ligands of the type [Fe{kappa N-2, N'-5-R-NC4H2-2-C(H)=N.2,6-iPr(2)-C6H3)}(Py)Cl], with R = 2,6-Me-2-C6H3 (1a), 2,4,6-Pr-i(3)-C6H2 (1b), 2,4,6-Ph-3-C6H3 (1c) and CPh3 (1d), were synthesized in moderate yields by reacting the respective 5-substituted-2-iminopyrrolyl potassium salts KLa-d with FeCl2(Py)(4) in toluene. Complexes 1a-d were characterized by H-1 NMR, FTIR spectroscopies, elemental analysis and by the Evans method, the corresponding effective magnetic moments showing a high-spin electronic nature. X-ray diffraction studies on complexes 1a and 1c showed distorted tetrahedral coordination geometries. Complexes 1a-c, activated with K(HBEt3), were efficient catalyst systems for the hydroboration of several terminal alkenes with pinacolborane in good to high yields (50-90%). This system mainly yielded the respective anti-Markovnikov addition products, except when styrenes were used. A screening of the hydroboration of styrene catalyzed by complexes 1a-c activated with K(HBEt3) showed that the selectivity in the Markovnikov product increased with increasing steric bulkiness of the R group, exhibiting selectivities up to 91%. Additionally, the stoichiometric reaction of complex 1b with K(HBEt3) over 30 minutes yielded the mixture of hydride species 2 and 2(2) (mixture I). On the other hand, when reacting the same components over 16 h, the Fe(I) complex 3 was also identified in the mixture, in addition to 2 + 2(2) (mixture II). These mixtures were characterized in solution by the Evans method and in the solid state by elemental analysis, Fe-57 Mossbauer and FTIR spectroscopies, compounds 2(2) and 3 being also analyzed by X-ray diffraction. These results suggest that the corresponding catalytic cycle follows the borane oxidative addition route to a Fe(I) species.
机译：四顺14-electron tetracoordinated5-substituted-2-iminopyrrolyl铁(II)配合物配体的类型(Fe {kappa n - 2,N ' 5-r-nc4h2-2-c (H) = N.2 6-iPr (2) -C6H3)} (Py) Cl),R = 2, 6-Me-2-C6H3 (1), 2, 4, 6-Pr-i (3) -C6H2(1 b), 2, 4, 6-Ph-3-C6H3 (1 c)和CPh3 (1 d)合成反应在温和的收益率各自5-substituted-2-iminopyrrolyl盐钾KLa-d FeCl2 (Py) (4)甲苯。核磁共振,红外光谱,元素分析埃文斯的方法,相应的有效显示一个高自旋电子磁矩大自然。和1 c显示扭曲的四面体协调几何图形。K (HBEt3),系统的高效催化剂硼氢化反应的末端烯烃pinacolborane好高收益率(50 - 90%)。这个系统主要是产生了各自的anti-Markovnikov添加产品,除非苯乙烯。通过配合物催化苯乙烯的硼氢化反应1 a - c激活与K (HBEt3)显示选择性的马氏产品增加随着空间庞大的R组,表现出选择性达到91%。复杂的化学计量反应1 bK (HBEt3)超过30分钟的混合物氢化物物种2和2 (2)(I)混合物的另一方面,当反应相同的组件在16 h, Fe (I) 3也是复杂的确定混合物中,除了2 +2 (2) (II)混合物,这些混合物在埃文斯的解决方案的方法和特点固态的元素分析,Fe-57穆斯堡尔和FTIR光谱,化合物2 (2)和3被x射线衍射分析。这些结果表明,对应的遵循硼烷氧化催化循环除了铁(I)的物种。

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