Synthesis, Characterization, and Dehydrogenation Activity of an Iridium Arsenic Based Pincer Catalyst
Synthesis, Characterization, and Dehydrogenation Activity of an Iridium Arsenic Based Pincer Catalyst
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DOI：
10.1021/om5005034
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发表时间：
2014-10-13
期刊：
影响因子：
2.8
通讯作者：
Jensen, Craig M.
中科院分区：
文献类型：
--
作者：
Brayton, Daniel F.;Beaumont, Paul R.;Jensen, Craig M.
合成了一种新的砷基钳形脱氢催化剂IrHCl{2，6-C6 H3-（O-AsBu 2 t）}（3）。在氢气气氛下用当量的碱（NaO-叔丁醇盐）处理得到二氢化物催化剂IrH 2 {2，6-C（6）H3-（O-AsBu 2 t）}（4）。在环辛烷和叔丁基乙烯的转移脱氢条件下探索了3的活性，在175 ℃下24 h内的最大转化数为960。还用吡咯烷基分子，乙基全氢咔唑（5）、甲基全氢吲哚（6）和丁基吡咯烷（7）探索了无受体双链反应，其中所有结果表明3的活性大致为类似的膦基钳形催化剂2的一半。类似于膦钳形催化剂，可以看到活性随着温度的升高而稳定地提高，在175 ° C达到峰值，在该温度下开始热分解。
A new arsenic-based pincer (AsOCOAs) dehydrogenation catalyst has been synthesized, IrHCl{2,6-C6H3-(O-AsBu2t)} (3). Treatment with an equivalent of base (NaO-tert-butoxide) under an atmosphere of hydrogen gas affords the dihydride catalyst IrH2{2,6-C(6)H3-(O-AsBu2t)} (4). The activity of 3 was explored under transfer dehydrogenation conditions with cyclooctane and tert-butyl ethylene, giving a maximum turnover number of 960 at 175 degrees C in 24 h. Acceptorless dehydrogenations were also explored with pyrrolidine-based molecules, ethylperhydrocarbazole (5), methylperhydroindole (6), and butylpyrrolidine (7), in which all results indicate 3 is roughly half as active as the analogous phosphine-based pincer catalyst 2. Akin to the phosphine pincer catalysts the activity was seen to steadily improve with increasing temperature, peaking at 175 degrees C, upon which thermal decomposition sets in.