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A β-diketiminate manganese catalyst for alkene hydrosilylation: substrate scope, silicone preparation, and mechanistic insight†
Chemical Science ( IF 8.4 ) Pub Date : 2018-08-15 00:00:00 , DOI: 10.1039/c8sc02768d
Tufan K Mukhopadhyay 1 , Marco Flores 1 , Thomas L Groy 1 , Ryan J Trovitch 1
Affiliation  

The dimeric β-diketiminate manganese hydride compound, [(2,6-iPr2PhBDI)Mn(μ-H)]2, was prepared by treating [(2,6-iPr2PhBDI)Mn(μ-Cl)]2 with NaEt3BH. This compound was characterized by single crystal X-ray diffraction and found to feature high-spin Mn centres that exhibit strong magnetic coupling by EPR spectroscopy. Once characterized, [(2,6-iPr2PhBDI)Mn(μ-H)]2 was found to mediate the hydrosilylation of a broad scope of alkenes at elevated temperature. Aliphatic alkenes were found to undergo anti-Markovnikov hydrosilylation, while the hydrosilylation of styrenes using [(2,6-iPr2PhBDI)Mn(μ-H)]2 afforded Markovnikov's product. Importantly, this catalyst has also been employed for the cross-linking of industrially-relevant silicones derived from vinyl-terminated poly(dimethylsiloxane) and 1,2,4-trivinylcyclohexane with catalyst loadings as low as 0.05 mol%. To gain a mechanistic understanding of [(2,6-iPr2PhBDI)Mn(μ-H)]2-catalyzed olefin hydrosilylation, 4-tert-butylstyrene was added to [(2,6-iPr2PhBDI)Mn(μ-H)]2 and conversion to the monomeric Mn alkyl complex, (2,6-iPr2PhBDI)Mn(CH(CH3)(4-tBuPh)), was observed. Isolation of this secondary alkyl intermediate confirms that olefin insertion into the Mn–H bond dictates the observed regioselectivities. The importance of our mechanistic findings as they relate to recent advances in Mn hydrosilylation catalysis is described herein.

中文翻译:

用于烯烃氢化硅烷化的 β-二酮亚胺锰催化剂:底物范围、有机硅制备和机理见解†

通过用 NaEt处理 [( 2,6-iPr2Ph BDI)Mn(μ-Cl)] 2制备二聚 β-二酮亚胺锰氢化物化合物 [( 2,6-iPr2Ph BDI)Mn(μ-H)] 2 3 BH。该化合物通过单晶 X 射线衍射表征,发现具有高自旋 Mn 中心,通过 EPR 光谱显示出强磁耦合。一旦表征,[( 2,6-iPr2Ph BDI)Mn(μ-H)] 2被发现在高温下介导大范围烯烃的氢化硅烷化。脂肪族烯烃被发现进行抗马尔科夫尼科夫氢化硅烷化,而苯乙烯的氢化硅烷化使用 [( 2,6-iPr2Ph BDI)Mn(μ-H)] 2提供马尔科夫尼科夫的产品。重要的是,该催化剂还用于交联工业相关的有机硅,这些有机硅衍生自乙烯基封端的聚(二甲基硅氧烷)和 1,2,4-三乙烯基环己烷,催化剂负载量低至 0.05 mol%。为了从机理上理解 [( 2,6-iPr2Ph BDI)Mn(μ-H)] 2 -催化烯烃氢化硅烷化,将 4-叔丁基苯乙烯添加到 [( 2,6-iPr2Ph BDI)Mn(μ-H) 中)] 2并转化为单体 Mn 烷基络合物, ( 2,6-iPr2Ph BDI)Mn(CH(CH 3 )(4- tBuPh)),观察到。这种仲烷基中间体的分离证实了烯烃插入 Mn-H 键决定了观察到的区域选择性。本文描述了我们的机理发现的重要性,因为它们与 Mn 氢化硅烷化催化的最新进展有关。
更新日期:2018-08-15
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