螯合双（亚氨基）吡啶钴配合物：合成、还原以及Li⁺阳离子活化生成乙烯聚合催化剂的证据

Chelate bis(imino)pyridine cobalt complexes: synthesis, reduction, and evidence for the generation of ethene polymerization catalysts by Li+ cation activation.

作者信息

Kleigrewe Nina, Steffen Winfried, Blömker Tobias, Kehr Gerald, Fröhlich Roland, Wibbeling Birgit, Erker Gerhard, Wasilke Julia-Christina, Wu Guang, Bazan Guillermo C

机构信息

Organisch-Chemisches Institut Universität Münster, Corrensstr. 40, D-48149 Münster, Germany.

出版信息

J Am Chem Soc. 2005 Oct 12;127(40):13955-68. doi: 10.1021/ja052129k.

DOI:10.1021/ja052129k

PMID:16201818

Abstract

Treatment of the bis(iminobenzyl)pyridine chelate Schiff-base ligand 8 (ligPh) with FeCl2 or CoCl2 yielded the corresponding (ligPh)MCl2 complexes 9 (Fe) and 10 (Co). The reaction of 10 with methyllithium or "butadiene-magnesium" resulted in reduction to give the corresponding (ligPh)Co(I)Cl product 11. Similarly, the bis(aryliminoethyl)pyridine ligand (ligMe) was reacted with CoCl2 to yield (ligMe)CoCl2 (12). Reduction to (ligMe)CoCl (13) was effected by treatment with "butadiene-magnesium". Complex 13 reacted with Li[B(C6F5)4] in toluene followed by treatment with pyridine to yield [(ligMe)Co+-pyridine] (15). The reaction of the Co(II) complexes 10 or 12 with ca. 3 molar equiv of methyllithium gave the cobalt(I) complexes 16 and 17, respectively. Treatment of the (ligMe)CoCH3 (17) with Li[B(C6F5)4] gave a low activity ethene polymerization catalyst. Likewise, complex 16 produced polyethylene (activity = 33 g(PE) mmol(cat)(-1) h(-1) bar(-1) at room temperature) upon treatment with a stoichiometric amount of Li[B(C6F5)4]. A third ligand (lig(OMe)) was synthesized featuring methoxy groups in the ligand backbone (22). Coordination to FeCl2 and CoCl2 yielded the desired compounds 23 and 24. Reaction with MeLi gave (ligOMe)CoMe (25/26). Treatment of 25/26 with excess B(C6F5)3 gave the eta6-arene cation complex 27, where one Co-N linkage was cleaved. Activation of 25/26 with Li[B(C6F5)4] again gave a catalytically active species.

摘要

用二氯化铁或二氯化钴处理双（亚氨基苄基）吡啶螯合席夫碱配体8（ligPh），得到相应的（ligPh）MCl₂配合物9（铁）和10（钴）。10与甲基锂或“丁二烯 - 镁”反应导致还原，得到相应的（ligPh）Co（I）Cl产物11。类似地，双（芳基亚氨基乙基）吡啶配体（ligMe）与二氯化钴反应生成（ligMe）CoCl₂（12）。用“丁二烯 - 镁”处理实现还原得到（ligMe）CoCl（13）。配合物13在甲苯中与Li[B（C₆F₅）₄]反应，然后用吡啶处理得到[(ligMe)Co⁺ - 吡啶]（15）。钴（II）配合物10或12与约3摩尔当量的甲基锂反应，分别得到钴（I）配合物16和17。用Li[B（C₆F₅）₄]处理（ligMe）CoCH₃（17）得到一种低活性的乙烯聚合催化剂。同样，配合物16在用化学计量的Li[B（C₆F₅）₄]处理后产生聚乙烯（室温下活性 = 33 g（PE）mmol⁻¹（cat）⁻¹ h⁻¹ bar⁻¹）。合成了第三种配体（lig（OMe）），其在配体主链中具有甲氧基（22）。与二氯化铁和二氯化钴配位得到所需化合物23和24。与甲基锂反应得到（ligOMe）CoMe（25/26）。用过量的B（C₆F₅）₃处理25/26得到η⁶ - 芳烃阳离子配合物27，其中一个Co - N键被切断。用Li[B（C₆F₅）₄]活化25/26再次得到一种催化活性物种。