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Increasing Olefin Metathesis Activity of Silica-Supported Molybdenum Imido Adamantylidene Complexes through E Ligand σ-Donation
Helvetica Chimica Acta ( IF 1.5 ) Pub Date : 2021-08-27 , DOI: 10.1002/hlca.202100151 Darryl F. Nater 1 , Bhaskar Paul 2 , Lukas Lätsch 1 , Richard R. Schrock 2 , Christophe Copéret 3
Helvetica Chimica Acta ( IF 1.5 ) Pub Date : 2021-08-27 , DOI: 10.1002/hlca.202100151 Darryl F. Nater 1 , Bhaskar Paul 2 , Lukas Lätsch 1 , Richard R. Schrock 2 , Christophe Copéret 3
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Molybdenum imido adamantylidene complexes with different substituents on the imido ligand (dipp=2,6-diisopropylphenyl, ArF5=C6F5, and tBu) having distinct electron donating abilities were investigated for the metathesis of internal and terminal olefins, for both molecular and silica-supported species using standardized protocols. Here we show that surface immobilization of these compounds results in dramatically increased activity compared to their molecular counterparts. Additionally, we show that electron withdrawing imido groups increase the activity of the compound towards terminal olefins while they simultaneously decrease the ability to metathesize internal olefins. Furthermore, these systems also show high stability when used as initiators in olefin metathesis, although the species that display higher initial activity deactivate faster than those that show more a more moderate reaction rate at first. Our catalytic studies, augmented by DFT calculations, show that all investigated compounds have a remarkably small energy difference between the trigonal bipyramidal (TBP) and square planar (SP) configurations of the metallacyclobutane intermediates, which has previously been linked to high activity.
中文翻译：
通过 E 配体 σ-捐赠提高二氧化硅负载的钼亚胺亚金刚烷配合物的烯烃复分解活性
亚胺配体上具有不同取代基的钼亚胺金刚烷基配合物（dipp=2,6-二异丙基苯基，Ar F5 =C 6 F 5，tbu) 研究了具有不同给电子能力的内部和末端烯烃的复分解，对于分子和二氧化硅支持的物种，使用标准化协议。在这里，我们表明，与它们的分子对应物相比，这些化合物的表面固定导致活性显着增加。此外，我们表明吸电子酰亚胺基团增加了化合物对末端烯烃的活性，同时它们降低了复分解内烯烃的能力。此外，这些系统在烯烃复分解反应中用作引发剂时也表现出高稳定性，尽管表现出较高初始活性的物质比起初表现出更温和反应速率的物质失活得更快。我们的催化研究，通过 DFT 计算增强，
更新日期：2021-08-27
中文翻译：
通过 E 配体 σ-捐赠提高二氧化硅负载的钼亚胺亚金刚烷配合物的烯烃复分解活性
亚胺配体上具有不同取代基的钼亚胺金刚烷基配合物（dipp=2,6-二异丙基苯基，Ar F5 =C 6 F 5，tbu) 研究了具有不同给电子能力的内部和末端烯烃的复分解，对于分子和二氧化硅支持的物种，使用标准化协议。在这里，我们表明，与它们的分子对应物相比，这些化合物的表面固定导致活性显着增加。此外，我们表明吸电子酰亚胺基团增加了化合物对末端烯烃的活性，同时它们降低了复分解内烯烃的能力。此外，这些系统在烯烃复分解反应中用作引发剂时也表现出高稳定性，尽管表现出较高初始活性的物质比起初表现出更温和反应速率的物质失活得更快。我们的催化研究，通过 DFT 计算增强，
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