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Platinum(II) Di-ω-alkenyl Complexes as “Slow-Release” Precatalysts for Heat-Triggered Olefin Hydrosilylation
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2021-10-13 , DOI: 10.1021/jacs.1c06846 Sumeng Liu 1 , Gregory S Girolami 1
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2021-10-13 , DOI: 10.1021/jacs.1c06846 Sumeng Liu 1 , Gregory S Girolami 1
Affiliation
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We describe the synthesis, characterization, and catalytic hydrosilylation activity of platinum(II) di-ω-alkenyl compounds of stoichiometry PtR2, where R = CH2SiMe2(vinyl) (1) or CH2SiMe2(allyl) (2), and their adducts with 1,5-cyclooctadiene (COD), dibenzo[a,e]cyclooctatetraene (DBCOT), and norbornadiene (NBD), which can be considered as slow-release sources of the reactive compounds 1 and 2. At loadings of 0.5 × 10–6–5 × 10–6 mol %, 1-COD is an active hydrosilylation catalyst that exhibits heat-triggered latency: no hydrosilylation activity occurs toward many olefin substrates even after several hours at 20 °C, but turnover numbers as high as 200000 are seen after 4 h at 50 °C, with excellent selectivity for formation of the anti-Markovnikov product. Activation of the PtII precatalyst occurs via three steps: slow dissociation of COD from 1-COD to form 1, rapid reaction of 1 with silane, and elimination of both ω-alkenyl ligands to form Pt0 species. The latent catalytic behavior, the high turnover number, and the high anti-Markovnikov selectivity are a result of the slow release of 1 from 1-COD at room temperature, so that the concentration of Pt0 during the initial stages of the catalysis is negligible. As a result, formation of colloidal Pt, which is known to cause side reactions, is minimized, and the amounts of side products are very small and comparable to those seen for platinum(0) carbene catalysts. The latent reaction kinetics and high turnover numbers seen for 1-COD after thermal triggering make this compound a potentially useful precatalyst for injection molding or solvent-free hydrosilylation applications.
中文翻译：
铂 (II) 二-ω-烯基配合物作为热触发烯烃氢化硅烷化的“缓释”预催化剂
我们描述了化学计量 PtR 2的铂 (II) 二-ω-烯基化合物的合成、表征和催化氢化硅烷化活性，其中 R = CH 2 SiMe 2 (乙烯基) ( 1 ) 或 CH 2 SiMe 2 (烯丙基) ( 2 )，以及它们与 1,5-环辛二烯 (COD)、二苯并 [ a , e ] 环辛四烯 (DBCOT) 和降冰片二烯 (NBD) 的加合物，它们可被视为反应性化合物1和2的缓释来源。负载量为 0.5 × 10 –6 –5 × 10 –6 mol %，1-COD是一种具有热触发潜伏期的活性氢化硅烷化催化剂：即使在 20 °C 下数小时后，对许多烯烃底物也不会发生氢化硅烷化活性，但在 50 °C 下 4 小时后可观察到高达 200000 的转换数，具有出色的选择性反马尔科夫尼科夫积的形成。Pt II预催化剂的活化通过三个步骤进行：COD 从 1-COD 缓慢解离形成 1，1与硅烷快速反应，以及消除两个 ω-烯基配体形成 Pt 0物质。潜在的催化行为、高周转数和高抗马尔科夫尼科夫选择性是1从1-COD中缓慢释放的结果在室温下，因此在催化的初始阶段Pt 0的浓度可以忽略不计。结果，已知会引起副反应的胶体 Pt 的形成被最小化，并且副产物的量非常小并且与铂（0）卡宾催化剂所见的那些相当。热触发后1-COD的潜伏反应动力学和高周转数使该化合物成为注塑成型或无溶剂氢化硅烷化应用中潜在有用的预催化剂。
更新日期：2021-10-27
中文翻译：
铂 (II) 二-ω-烯基配合物作为热触发烯烃氢化硅烷化的“缓释”预催化剂
我们描述了化学计量 PtR 2的铂 (II) 二-ω-烯基化合物的合成、表征和催化氢化硅烷化活性，其中 R = CH 2 SiMe 2 (乙烯基) ( 1 ) 或 CH 2 SiMe 2 (烯丙基) ( 2 )，以及它们与 1,5-环辛二烯 (COD)、二苯并 [ a , e ] 环辛四烯 (DBCOT) 和降冰片二烯 (NBD) 的加合物，它们可被视为反应性化合物1和2的缓释来源。负载量为 0.5 × 10 –6 –5 × 10 –6 mol %，1-COD是一种具有热触发潜伏期的活性氢化硅烷化催化剂：即使在 20 °C 下数小时后，对许多烯烃底物也不会发生氢化硅烷化活性，但在 50 °C 下 4 小时后可观察到高达 200000 的转换数，具有出色的选择性反马尔科夫尼科夫积的形成。Pt II预催化剂的活化通过三个步骤进行：COD 从 1-COD 缓慢解离形成 1，1与硅烷快速反应，以及消除两个 ω-烯基配体形成 Pt 0物质。潜在的催化行为、高周转数和高抗马尔科夫尼科夫选择性是1从1-COD中缓慢释放的结果在室温下，因此在催化的初始阶段Pt 0的浓度可以忽略不计。结果，已知会引起副反应的胶体 Pt 的形成被最小化，并且副产物的量非常小并且与铂（0）卡宾催化剂所见的那些相当。热触发后1-COD的潜伏反应动力学和高周转数使该化合物成为注塑成型或无溶剂氢化硅烷化应用中潜在有用的预催化剂。
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